HU Range Research Articles

Proton CT on biological phantoms for x-ray CT calibration in proton treatment planning

Objective. To present and characterize a novel method for x-ray computed tomography (xCT) calibration in proton treatment planning, based on proton CT (pCT) measurements on biological phantoms. Approach. A pCT apparatus was used to perform direct measurements of 3D stopping power relative to water (SPR) maps on stabilized, biological phantoms. Two single-energy xCT calibration curves—i.e. tissue substitutes and stoichiometric—were compared to pCT data. Moreover, a new calibration method based on these data was proposed, and verified against intra- and inter-species variability, dependence on stabilization, beam-hardening conditions, and analysis procedures. Main results. Biological phantoms were verified to be stable in time, with a dependence on temperature conditions, especially in the fat region: (−2.5 土 0.5) HU °C−1. The pCT measurements were compared with standard xCT calibrations, revealing an average SPR discrepancy within ±1.60% for both fat and muscle regions. In the bone region the xCT calibrations overestimated the pCT-measured SPR of the phantom, with a maximum discrepancy of about +3%. As a result, a new cross-calibration curve was directly extracted from the pCT data. Overall, the SPR uncertainty margin associated with this curve was below 3%; fluctuations in the uncertainty values were observed across the HU range. Cross-calibration curves obtained with phantoms made of different animal species and anatomical parts were reproducible with SPR discrepancies within 3%. Moreover, the stabilization procedure did not affect the resulting curve within a 2.2% SPR deviation. Finally, the cross-calibration curve was affected by the beam-hardening conditions on xCTs, especially in the bone region, while dependencies below 2% resulted from the image registration procedure. Significance. Our results showed that pCT measurements on biological phantoms may provide an accurate method for the verification of current xCT calibrations and may represent a tool for the implementation of a new calibration method for proton treatment planning.

Technical and clinical considerations of a physical liver phantom for CT radiomics analysis.

This study identifies key characteristics to help build a physical liver computed tomography (CT) phantom for radiomics harmonization; particularly, the higher-order texture metrics. CT scans of a radiomics phantom comprising of 18 novel 3D printed inserts with varying size, shape, and material combinations were acquired on a 64-slice CT scanner (Brilliance 64, Philips Healthcare). The images were acquired at 120kV, 250mAs, CTDIvol of 16.36mGy, 2mm slice thickness, and iterative noise-reduction reconstruction (iDose, Philips Healthcare, Andover, MA). Radiomics analysis was performed using the Cancer Imaging Phenomics Toolkit (CaPTk), following automated segmentation of 3D regions of interest (ROI) of the 18 inserts. The findings were compared to three additional ROI obtained of an anthropomorphic liver phantom, a patient liver CT scan, and a water phantom, at comparable imaging settings. Percentage difference in radiomic metrics values between phantom and tissue was used to assess the biological equivalency and <10% was used to claim equivalent. The HU for all 18 ROI from the phantom ranged from -30 to 120 which is within clinically observed HU range of the liver, showing that our phantom material (T3-6B) is representative of biological CT tissue densities (liver) with >50% radiomic features having <10% difference from liver tissue. Based on the assessment of the Neighborhood Gray Tone Difference Matrix (NGTDM) metrics it is evident that the water phantom ROI show extreme values compared to the ROIs from the phantom. This result may further reinforce the difference between a structureless quantity such as water HU values and tissue HU values found in liver. The 3-D printed patterns of the constructed radiomics phantom cover a wide span of liver tissue textures seen in CT images. Using our results, texture metrics can be selectively harmonized to establish clinically relevant and reliable radiomics panels.

Image-Guided IORT after Surgical Resection of Brain Malignancies: A Feasibility Study

Intraoperative radiation therapy (IORT) can be used to locally apply radiation doses to surgical cavities of resected brain metastases and glioblastoma. The miniaturized linear accelerator INTRABEAM 600® offers a low-energy system of 50kV X-rays. To date, placing the spherical applicator in the surgical bed has been done manually and without final positioning verification. Ultimately, without positional control, it must be assumed that the applicator is optimally positioned against the tissue in the tumor cavity, without any air interference or fluid underlying. Misplacements could lead to incomplete dose delivery, potentially yielding an increased risk of recurrence. Therefore, we deemed relevant to assess intraoperative imaging as a novel option for easing the applicator positioning. A surgical environment was mimicked in two test runs with an interdisciplinary team, accounting for operating and anesthesia times. The IORT planning software Radiance (GMV Innovating Solutions, Madrid, Spain) was previously calibrated with a "cheese" phantom, using twelve different density levels from 0.3 to 1.842 g/cm3, yielding a value-to-density table with -600 to +600 HU range. Furthermore, two inserts were placed in the phantom to evaluate the quality and spatial resolution of the cone-beam CT (CBCT) imaging. The O-Arm System (Medtronic, Minneapolis, MN, USA) was employed for acquiring tomographic intraoperative imaging, once the applicator was placed in a skull-shaped phantom. Two expert radiation oncologists contoured the acquired dataset and performed the treatment calculations, based on a 30 Gy prescription dose. We achieved the best possible CBCT imaging quality with the 120kV and 20mA setting parameters. This corresponds to the "HD3D (large)" O-Arm setting mode. With this, the image quality with artifact reduction, minimization of image noise and consideration of a low radiation exposure of only 0.5mSv for the patients is feasible. Approximately 15 additional minutes were accounted for contouring and planning times. Good-quality intraoperative imaging can be obtained when performing IORT, easing the applicator positioning and resulting in a more precise target irradiation. Operating times would be minimally extended with this procedure. A clinical study will initiate based on these findings.

Abstract P1-03-04: Visceral fat area as a predictive factor in metastatic HER2 negative breast cancer patients treated by first line chemotherapy with weekly paclitaxel and bevacizumab

Abstract Background Obesity has previously been correlated with poorer survival in both early and metastatic breast cancer. Adipose tissues release proangiogenic factors such as Insulin-like Growth Factor and Vascular Endothelial Growth Factor that may ultimately promote tumor growth. CTscan can be used to measure the visceral fat area (VFA) and the subcutaneous fat area (SFA) on the same section. High VFA has been shown to independently predict poorer outcome in patients given first-line bevacizumab-based treatment for metastatic colorectal cancer and metastatic renal cell carcinoma. The prospective multicenter COMET trial included metastatic HER2 negative breast cancer patients receiving bevacizumab and paclitaxel as fist-line chemotherapy. This study was designed to identify and validate reliable factors to predict benefit of bevacizumab and allow for a more personalized use of this antiangiogenic agent. Our aim was to evaluate the prognostic value of BMI (Body Mass Index), VFA and SFA in the COMET cohort and their impact on the quality of life. Patients and Methods Out of the 510 patients included in the COMET trial from 9/2012 to 3/2016, 480 received bevacizumab and paclitaxel as first-line treatment and 360 had available CTscan data. VFA and SFA were measured retrospectively on the CTscans performed before chemotherapy initiation, at the level of the umbilicus with the patient in the supine position. ImageJ software was used to measure pixels with densities in the -190 HU to -30 HU range in order to delineate the subcutaneous and visceral compartments and to compute the cross-sectional area of each in cm2. These measurements were performed by a radiologist blinded to patients’ characteristics and outcomes. For VFA and SFA, we used a threshold at the median value. VFA and SFA levels were tested for their association with progression-free survival (PFS) and overall survival (OS). The impact on quality of life was based on the Global Health Status, the Physical functioning, the Emotional functioning, Fatigue and Pain scores. Results The mean age at inclusion was 57 years (range: 28-83). At initial diagnosis, the main histological type was invasive ductal carcinoma (n = 247, 80.7%). Most patients had received prior neoadjuvant/adjuvant chemotherapy (n = 245, 68.1%) and a large majority (95.4%) had less than 3 metastatic sites. One hundred and forty patients (46.7%) had histological grade II and 41% had grade III tumors. The majority of the patients had positive hormone receptor tumor (n = 238, 79.3 %) and 62 (20.7%) had triple-negative tumor subtype. The median BMI was 24.7 (range : 17-46). After a median follow-up of 60.6 months (95%CI, 60-61.3), median PFS was 9.5 months (95CI, 8.6-10.3). There was no significant correlation between BMI (p = 0.69), VFA (p = 0.24) or SFA (p = 0.58) and PFS in the univariate analysis. The median OS was 29.6 months (95CI, 25.9-32.4). BMI, VFA and SFA were not correlated with OS. Out of the 360 patients, 328 had available data regarding the quality of life. There was no impact of the VFA or the SFA on the different quality of life scores. Conclusions In our prospective cohort of 360 patients with metastatic breast cancer receiving bevacizumab and paclitaxel as first-line treatment, high VFA or high SFA were not associated with a poorer survival. VFA and SFA had no impact on quality of life. Citation Format: Séverine Guiu, Boris Guiu, Marion Chevrier, Oumar Billa, Christelle Levy, Olivier Trédan, Isabelle Desmoulins, Marc Debled, Jean-Marc Ferrero, Christelle Jouannaud, Anthony Gonçalves, Maria Rios, Marie-Ange Mouret-Reynier, Frédérique Berger, Fatima-Zohra TOUMI, Jérôme Lemonnier, Jean-Yves Pierga, Sandrine Dabakuyo, Sophie Gourgou. Visceral fat area as a predictive factor in metastatic HER2 negative breast cancer patients treated by first line chemotherapy with weekly paclitaxel and bevacizumab [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr P1-03-04.

Minipercutaneous Nephrolithotomy in the Management of Large and Complex Renal Calculi in Children: How Effective Is It?

Purpose: To evaluate the efficacy and safety of minipercutaneous nephrolithotomy (PCNL) in the management of large and complex calculi in children. Patients and Methods: From May 2017 to April 2021, a total of 41 pediatric cases were diagnosed with large/complex renal stones (partial-total staghorn) and following a detailed biochemical evaluation and thorough radiological examination (plain abdominal radiograph, urinary ultrasound, noncontrast and/or computed tomography), all cases underwent mini-PCNL procedure for the minimal invasive management of these calculi. Preoperative, intraoperative, and postoperative data were analyzed and reported in detail. Results: A total of 41 procedures were performed in 26 boys and 15 girls (male/female = 1.73). While the age of the kids ranged from 2.5 to 10 years (mean 6.74 ± 2.76), mean size of the stones was 16.28 ± 3.43 mm (range 11-24) with a mean stone density value of 816 HU (range 550-1350). Evaluation of the success rates in terms of complete stone clearance on postoperative day 1 revealed that while 73.2% (30/41), residual fragments have been noted in 11 cases (26.8%). Size of the residual fragments ranged from 2 to 7 mm (mean 4.3). Of those children, 10 cases required flexible ureteroscopy for stone removal, and in 1 case, placement of Double-J was adequate for spontaneous passage. During a 3-month follow-up, the stone-free rate (SFR) increased to 100% without any residual fragment left. Conclusions: Mini-PCNL with holmium laser lithotripsy is an effective and safe treatment alternative in the minimal invasive management of large/complex kidney stones in children with high SFRs.

Realistic 3D printed CT imaging tumor phantoms for validation of image processing algorithms

Medical imaging phantoms are widely used for validation and verification of imaging systems and algorithms in surgical guidance and radiation oncology procedures. Especially, for the performance evaluation of new algorithms in the field of medical imaging, manufactured phantoms need to replicate specific properties of the human body, e.g., tissue morphology and radiological properties. Additive manufacturing (AM) technology provides an inexpensive opportunity for accurate anatomical replication with customization capabilities. In this study, we proposed a simple and cheap protocol using Fused Deposition Modeling (FDM) technology to manufacture realistic tumor phantoms based on the filament 3D printing technology. Tumor phantoms with both homogenous and heterogeneous radiodensity were fabricated. The radiodensity similarity between the printed tumor models and real tumor data from CT images of lung cancer patients was evaluated. Additionally, it was investigated whether a heterogeneity in the 3D printed tumor phantoms as observed in the tumor patient data had an influence on the validation of image registration algorithms.A radiodensity range between −217 to 226 HUs was achieved for 3D printed phantoms using different filament materials; this range of radiation attenuation is also observed in the human lung tumor tissue. The resulted HU range could serve as a lookup-table for researchers and phantom manufactures to create realistic CT tumor phantoms with the desired range of radiodensities. The 3D printed tumor phantoms also precisely replicated real lung tumor patient data regarding morphology and could also include life-like heterogeneity of the radiodensity inside the tumor models. An influence of the heterogeneity on accuracy and robustness of the image registration algorithms was not found.

Second-look flexible ureteroscopy after RIRS - Holmium Moses versus TFL (Soltive).

Retrograde intrarenal surgery (RIRS) is nowadays more and more indicated in pyelocaliceal stones. Holmium and Thulium lasers are the main lasers used. Fragmenting (basketing) or dusting, despite the new technology, still have residual stones (even having 250 microns). This study evaluates second-look flexible ureteroscopy for residual fragments. We analyzed 246 patients (October 2020-March 2022) on which we used Moses Holmium technology (187 cases) in Group 1 and Soltive Laser System (59 cases) in Group 2. The average stone size was 13.1 mm (range 11-29), and the average stone density was 1026 HU (range 870-1752). We used 270 µm for Ho: YAG laser and 150 µm for TFL. For Holmium, we applied energy 0.4J and frequency 80 Hz. For TFL, we applied fine dusting (0.15 J/100 Hz) and dusting (0.5 J/30 Hz). After three months, we practiced the second flexible ureteroscopy. Both groups were compared for completely visual stone-free rates. Stone-free rate at 3 months (second flexible ureteroscopy) was 86.63% (n=162/187) in Group 1 and 96,61% (n=57/59) in Group 2, respectively. The stone-free correlation with the CT preoperative evaluation was 160/187-85.56% for Holmium and 55/59-93.22% for TFL. We found residual stones after the second flexible ureteroscopy in 25 cases after Holmium laser treatment and only in 2 cases after TFL. In all these cases, we finally obtained zero residual stones. The second flexible ureteroscopy could achieve complete residual stone removal and real stone-free status. Despite a slight difference between these two laser technologies, the second look decreases the residual fragments.

Physical characteristics in cone beam computed Tomography (CBCT) imaging for small motion target in different directions

Purpose: Fiducial marker has been an effective and intuitive way to localize motion target for lung Stereotactic Body Radiotherapy (SBRT). However, due to the complexity for motion target imaging, the optimal target localization strategy still need to be developed to improve the efficiency and effectiveness of the clinical procedure. In this study, the golden marker moving in different directions was characterized in CBCT images for optimal localization application. Method and Materials: A Visicoil linear fiducial marker was selected for this study. The length and diameter of the marker were 5mm and 1mm. The motion was generated by Real Time Position Management (RPM) phantom from Varian Medical System. The motion was simulated to be 2.3 second breathing period and about 1cm amplitude. The motion was at three directions along the anterior-posterior (AP), left-right (LR), and In-Out (IO) of the couch. Their CBCT images were taken, and targets were done by auto-contouring with HU range from minus 900 to positive 4000. The targets were post-processed with keeping the largest part and converted to high resolution segment. Their characteristics were described by shape, volume, center of the volume and volume pixel information, which were attained by MIM Software. Results: In this CBCT study, the volume of motion visicoil gold maker were 0.283cc, 0.348cc, and 0.271cc as moving along AP, IO and LR direction. They were corresponding to 143%, 163% and 236% of the static volume. The max HUs for each moving target were 3395, 343 and 3097, which were 49 %, 13% and 44% of those of the static visicoil. The center distances comparing to those of the static targets were 0.63cm with standard deviation at 0.02cm. Conclusions: When the gold makers were applied for localization of treatment target in Lung SBRT, the geometric distance can be reflected in accurate level; however, the direction of motions could generate large HU difference, which could be one of factors resulted in local failure due to undefined boundary of tumor. And dosimetric characteristic in region of interest should be further investigated to understand the potential effect of local failure case even when marker tracking or soft tissue technique for localization is used.

Arterial stiffness and atherosclerosis in systemic lupus erythematosus patients

IntroductionSystemic lupus erythematosus (SLE) is characterized by early atherothrombosis. Pulse wave velocity (PWV) is a promising tool for the diagnosis of early vascular remodelling and initial atherosclerotic plaque formation. Our objective was to evaluate PWV and its relationship with coronary atherosclerosis and thrombotic biomarkers in patients with SLE.Material and methodsIn 26 patients with SLE with stable clinical conditions, mean age of 39.1 ±11.7 years and without a history of coronary artery disease, multidetector computed tomography (MDCT)-based coronary calcium scoring (CACS) was performed and PWV measured.Laboratory evaluation included serum levels of anticardiolipin and anti-β2-glycoprotein antibodies (anti-β2-GPI), lupus anticoagulant (LA), D-dimers, thrombin–antithrombin complexes (TAT), and von Willebrand factor (vWF).ResultsMultidetector computed tomography revealed coronary calcifications in 8 (30.8%) patients and the median CACS was 52.4 HU (range 2–843.2). The mean PWV was 9.0 ±3.2 m/s and was higher in patients aged > 50 years (+33.7% vs. < 50 years), those with positive LA (+28.2% vs. LA negative), TAT ≥ 10 μg/l (+18.1% vs. < 10 μg/l), vWF ≥ 200 IU/dl (+51.8% vs. < 200 IU/dl) and with coronary atherosclerosis (CACS > 0; +21.4% vs. CACS = 0).In contrast, the duration of the disease, D-dimers, anticardiolipin, and anti-β2-GPI antibodies did not influence PWV. In the group without atherosclerosis (CACS = 0, n =18), patients with vWF ≥ 200 IU/dl had a 19.3% higher PWV compared to the rest.ConclusionsIn patients with SLE, PWV was associated with the presence of coronary atherosclerotic lesions in MDCT. Furthermore, arterial stiffness was higher in patients with markers of endothelial dysfunction and a prothrombotic state, suggesting their contribution to the early stages of arterial remodelling in SLE.

Acquired cystic disease subtype renal cell carcinoma (ACD-RCC): prevalence and imaging features at a single institution.

Acquired cystic kidney disease (ACKD) is commonly seen in patients with end-stage renal disease (ESRD), and patients with ACKD have an increased risk of renal cell carcinoma (RCC). Acquired cystic disease-associated RCC (ACD-RCC) was incorporated into the 2016 World Health Organization Classification. This study aims to describe the imaging features of ACD-RCC, which are not well reported previously. Retrospective review of patients with ACKD who underwent total nephrectomy for concern of a renal mass between 2016 and 2021 yielded 122 nephrectomies in 107 patients. Pathology reports were searched for type and subtype of mass. In ACD-RCC subtypes, imaging studies were evaluated for modality and contrast enhancement (CE). Imaging findings assessed included cystic/solid nature, unenhanced CT (NECT) attenuation, enhancement characteristics [non-enhancing (< 10 HU difference), equivocal (10-20 HU), enhancing (> 20 HU)], subjective MRI enhancement, T1 and T2 signal intensity, restricted diffusion, ultrasound (US) echogenicity, and subjective CEUS enhancement. 148 masses were identified, 122 (82%) of which were malignant and 26 (18%) benign. The three most common tumors were clear cell RCC (n = 47), papillary RCC (n = 35), and ACD-RCC (n = 21). Of the 21 cases of ACD-RCC, 16 had preoperative imaging: CT (15: 6 NECT only, 2 CECT only, 7 combined NECT and CECT), MRI (4), CEUS (5). Ten of these tumors were solid/mostly solid and 6 mixed cystic/solid. On NECT, the average attenuation was 35 HU (range 13-52). Of those with multiphasic CTs, 1 was non-enhancing, 3 were equivocal, and 3 enhanced. All 3 masses imaged with CE-MRI showed enhancement. All 4 tumors evaluated by MRI demonstrated T2 hypointensity and restricted diffusion. All five masses enhanced on CEUS. ACD-RCC subtype was the third most common renal neoplasm in ACKD patients. Our findings found that no single imaging feature is pathognomonic for ACD-RCC. However, ACD-RCCs are typically solid masses with most demonstrating equivocal or mild enhancement on CT. T2 hypointensity and restricted diffusion were the most common MRI features.

Classification of X-Ray Attenuation Properties of Additive Manufacturing and 3D Printing Materials Using Computed Tomography From 70 to 140 kVp

Additive manufacturing and 3D printing is particularly useful in the production of phantoms for medical imaging applications including determination and optimization of (diagnostic) image quality and dosimetry. Additive manufacturing allows the leap from simple slab and stylized to (pseudo)-anthropomorphic phantoms. This necessitates the use of materials with x-ray attenuation as close as possible to that of the tissues or organs mimicked. X-ray attenuation properties including their energy dependence were determined for 35 printing materials comprising photocured resins and thermoplastic polymers. Prior to measuring x-ray attenuation in CT from 70 to 140 kVp, printing parameters were thoroughly optimized to ensure maximum density avoiding too low attenuation due to microscopic or macroscopic voids. These optimized parameters are made available. CT scanning was performed in a water filled phantom to guarantee defined scan conditions and accurate HU value determination. The spectrum of HU values covered by polymers printed using fused deposition modeling reached from −258 to +1,063 at 120 kVp (−197 to +1,804 at 70 kVp, to −266 to +985 at 140 kVp, respectively). Photocured resins covered 43 to 175 HU at 120 kVp (16–156 at 70, and 57–178 at 140 kVp). At 120 kVp, ASA mimics water almost perfectly (+2 HU). HIPS (−40 HU) is found close to adipose tissue. In all photocurable resins, and 17 printing filaments HU values decreased with increasing beam hardness contrary to soft tissues except adipose tissue making it difficult to mimic water or average soft tissue in phantoms correctly over a range of energies with one single printing material. Filled filaments provided both, the HU range, and an appropriate energy dependence mimicking bone tissues. A filled material with almost constant HU values was identified potentially allowing mimicking soft tissues by reducing density using controlled under-filling. The measurements performed in this study can be used to design phantoms with a wide range of x-ray contrasts, and energy dependence of these contrasts by combining appropriate materials. Data provided on the energy dependence can also be used to correct contrast or contrast to noise ratios from phantom measurements to real tissue contrasts or CNRs.

Improved precision of noise estimation in CT with a volume-based approach

Assessment of image noise is a relevant issue in computed tomography (CT). Noise is routinely measured by the standard deviation of density values (Hounsfield units, HU) within a circular region of interest (ROI). We explored the effect of a spherical volume of interest (VOI) on noise measurements. Forty-nine chronic obstructive pulmonary disease patients underwent CT with clinical protocol (regular dose [RD], volumetric CT dose index [CTDIvol] 3.04 mGy, 64-slice unit), and ultra-low dose (ULD) protocol (median CTDIvol 0.38 mGy, dual-source unit). Noise was measured in 27 1-cm2 ROIs and 27 0.75-cm3 VOIs inside the trachea. Median true noise was 21 HU (range 17-29) for RD-CT and 33 HU (26-39) for ULD-CT. The VOI approach resulted in a lower mean distance between limits of agreement compared to ROI: 5.9 versus 10.0 HU for RD-CT (−40%); 4.7 versus 9.9 HU for ULD-CT (−53%). Mean systematic bias barely changed: −1.6 versus −0.9HU for RD-CT; 0.0 to 0.4HU for ULD-CT. The average measurement time was 6.8 s (ROI) versus 9.7 (VOI), independent of dose level. For chest CT, measuring noise with a VOI-based instead of a ROI-based approach reduces variability by 40-53%, without a relevant effect on systematic bias and measurement time.

PD21-01 OUTCOMES AND RATES OF DISSOLUTION THERAPY FOR URIC ACID STONES

You have accessJournal of UrologyStone Disease: Medical & Dietary Therapy (PD21)1 Sep 2021PD21-01 OUTCOMES AND RATES OF DISSOLUTION THERAPY FOR URIC ACID STONES Jonathan Moore, Amihay Nevo, Saif Salih, Haidar Abdul-Muhsin, Mira Keddis, Karen Stern, and Mitchell Humphreys Jonathan MooreJonathan Moore More articles by this author , Amihay NevoAmihay Nevo More articles by this author , Saif SalihSaif Salih More articles by this author , Haidar Abdul-MuhsinHaidar Abdul-Muhsin More articles by this author , Mira KeddisMira Keddis More articles by this author , Karen SternKaren Stern More articles by this author , and Mitchell HumphreysMitchell Humphreys More articles by this author View All Author Informationhttps://doi.org/10.1097/JU.0000000000002010.01AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookLinked InTwitterEmail Abstract INTRODUCTION AND OBJECTIVE: To describe the outcomes and quantify the rate of uric acid stone medical dissolution therapy using automated, software-generated stone volume measurements METHODS: A sample of patients treated with oral dissolution therapy was reviewed from a single institution between 2008 and 2019. Baseline patient demographics, metabolic urine testing and stone characteristics were collected. CT scan images were evaluated using the quantitative Stone Analysis Software (qSAS) to obtain total stone volume (TSV), maximum diameter (MD) and stone number. Rate of dissolution using TSV was calculated over the treatment period. RESULTS: A total of 27 patients were started on oral dissolution therapy, corrected for renal function. After mean treatment duration of 180 days (range 41-531), 16 patients failed treatment due to intolerance (2), lack of pH change (2), compliance with medication (6) and resistance of stone (6), resulting in surgical therapy. Twenty stones in 11 patients showed complete (CD) or partial dissolution (PD) and were analyzed with the qSAS software. Compared to those who failed treatment, CD and PD patients had lower 24 h urinary uric acid (0.6 vs. 1.7 g/day, p=0.025) and higher treatment urine pH (6.8 vs 5.9, p<0.001). Pre-treatment stone burden had a MD 16.6 mm (range 4.5-40.4), TSV 1014 mm3 (range 27-4939) and attenuation 354.8 HU (range 22-455). Thirteen (65%) stones showed CD on imaging. Time to CD was 167.6 days (SD 82.9, range 41-312). CD patients had a significantly lower HU than PD (291.8 vs. 392 HU, p=0.005). Rate of change for responders was 4.73 mm3 or 0.6% of TSV per day. Time to dissolution of 50% of stone volume based on TSV was 86 days (12.30 weeks). MD overestimated the time to 50% of stone volume by 72.1 days (10.3 weeks). CONCLUSIONS: Use of software-calculated TSV is an effective method of measuring uric acid stone response to oral alkalization therapy. Stone volume decreased by 50% after 12.3 weeks of treatment. Further studies with a larger sample are needed to confirm if this can be used to guide surveillance schedules for dissolution therapy. Source of Funding: None © 2021 by American Urological Association Education and Research, Inc.FiguresReferencesRelatedDetails Volume 206Issue Supplement 3September 2021Page: e373-e373 Advertisement Copyright & Permissions© 2021 by American Urological Association Education and Research, Inc.MetricsAuthor Information Jonathan Moore More articles by this author Amihay Nevo More articles by this author Saif Salih More articles by this author Haidar Abdul-Muhsin More articles by this author Mira Keddis More articles by this author Karen Stern More articles by this author Mitchell Humphreys More articles by this author Expand All Advertisement Loading ...

Investigating the impact of the CT Hounsfield unit range on radiomic feature stability using dual energy CT data

<h2>Abstract</h2><h3>Purpose</h3> Radiomic texture calculation requires discretizing image intensities within the region-of-interest. FBN (fixed-bin-number), FBS (fixed-bin-size) and FBN and FBS with intensity equalization (FBNequal, FBSequal) are four discretization approaches. A crucial choice is the voxel intensity (Hounsfield units, or HU) binning range. We assessed the effect of this choice on radiomic features. <h3>Methods</h3> The dataset comprised 95 patients with head-and-neck squamous-cell-carcinoma. Dual energy CT data was reconstructed at 21 electron energies (40, 45,… 140 keV). Each of 94 texture features were calculated with 64 extraction parameters. All features were calculated five times: original choice, left shift (-10/-20 HU), right shift (+10/+20 HU). For each feature, Spearman correlation between nominal and four variants were calculated to determine feature stability. This was done for six texture feature types (GLCM, GLRLM, GLSZM, GLDZM, NGTDM, and NGLDM) separately. This analysis was repeated for the four binning algorithms. Effect of feature instability on predictive ability was studied for lymphadenopathy as endpoint. <h3>Results</h3> FBN and FBNequal algorithms showed good stability (correlation values consistently <mml:math><mml:mrow><mml:mo>></mml:mo></mml:mrow></mml:math>0.9). For FBS and FBSequal algorithms, while median values exceeded 0.9, the 95% lower bound decreased as a function of energy, with poor performance over the entire spectrum. FBNequal was the most stable algorithm, and FBS the least. <h3>Conclusions</h3> We believe this is the first multi-energy systematic study of the impact of CT HU range used during intensity discretization for radiomic feature extraction. Future analyses should account for this source of uncertainty when evaluating the robustness of their radiomic signature.

Analysis of factors affecting the diagnostic yield of image-guided percutaneous core needle biopsy for peritoneal/omental lesions.

To evaluate the diagnostic yield, safety, and factors associated with the diagnostic yield of percutaneous core needle biopsy (PNB) for peritoneal/omental lesions. Consecutive 297 patients (67 men, 230 women; median age, 64years [range 15-87]) who underwent a PNB for 311 peritoneal/omental lesions at a single center from April 2010 to March 2020 were evaluated retrospectively. The preprocedural CT findings, diagnostic yield, sensitivity, specificity, PPV, NPV, technical success rate, and adverse events were analyzed. Surgical or clinical diagnosis with follow-up was the diagnostic reference standard. Adverse events were evaluated using the Society of Interventional Radiology guidelines. The median anteroposterior (AP) diameter and CT value of the target lesion were 24mm (range 5-78) and 46 HU (range -75 to 140), respectively. Ascites was interposed on the puncture route in 106 patients (34.1%). The technical success rate was 100%. The diagnostic yield, sensitivity, specificity, PPV, and NPV were 93.9%, 93.8%, 100%, 100%, and 20.8%, respectively. Minor complications were observed following five procedures (1.6%). The diagnostic yield was lower for fat-dominant lesions than for other lesions (82.6% vs. 95.8%, p = 0.002). The diagnostic PNB group had a greater AP diameter than did the non-diagnostic PNB group (27.3 ± 13.0 vs. 20.7 ± 8.4mm, p = 0.037). PNB for peritoneal/omental lesions provided a sufficiently high diagnostic yield and minimal adverse events. Lesions with a greater AP diameter and a higher density on CT would provide more diagnostic specimens from this technique.

Technical aspects to maximize the hyperaccuracy three-dimensional (HA3D™) computed tomography reconstruction for kidney stones surgery: a pilot study.

The aim of the current prospective pilot study was to describe a hyperaccuracy three-dimensional (HA3D™) model reconstruction technique, specifically developed to maximize the visualization of the renal collecting system's anatomy, and its relationship with the stones, vessels and renal parenchyma, and to compare the HA3D™ virtual models with the intraoperative findings. The image acquisition was performed using a CT scanner (Toshiba, Aquilion Prime) and included the unenhanced, arterial, venous and excretory phases. The DICOM format CT images were processed by MEDICS Srl ( www.medics3d.com , Turin, Italy). In total, study included three patients with renal stone scheduled for non-papillary prone percutaneous nephrolithotomy (PCNL). The median age and BMI were 51 (range 49-54) and 25.5 (range 25.0-32.7), respectively. The median stone size was 1170 mm2 (range 830-1520) and median stone density was 1130 HU (range 600-1340). In all cases, the quality of the CT images acquired with our protocol was adequate to perform the HA3D™ reconstruction. Median operative and puncture time were 39.4 (range 35.2-44.0) and 1.9 (range 1.8-2.1) mins, respectively. The success rate for the first attempt of the percutaneous puncture was 100%, and only one PCNL tract was sufficient to complete the surgery. All three patients were stone-free on the third postoperative day. A dedicated imaging acquisition protocol and a tailored 3D model reconstruction process specifically developed for kidney stones treatment allow obtaining HA3D™ highly relevant models to greatly match intraoperative findings during PCNL with the potential of minimizing bleeding and organ injury complications.

Abdominal vessel depiction on virtual triphasic spectral detector CT: initial clinical experience

PurposeTo evaluate vessel assessment in virtual monoenergetic images (VMI40keV) and virtual-non-contrast images (VNC) derived from venous phase spectral detector computed tomography (SDCT) acquisitions in comparison to arterial phase and true non-contrast (TNC) images.MethodsTriphasic abdominal SDCT was performed in 25 patients including TNC, arterial and venous phase. VMI40keV and VNC were reconstructed from the venous phase and compared to conventional arterial-phase images (CIart), TNC and conventional venous-phase images (CIven). Vessel contrast and virtual contrast removal were analyzed with region-of-interest-based measurements and in a qualitative assessment.ResultsQuantitative analysis revealed no significant attenuation differences between TNC and VNC in arterial vessels (p-range 0.07–0.47) except for the renal artery (p = 0.011). For venous vessels, significant differences between TNC and VNC were found for all veins (p < 0.001) except the inferior vena cava (p = 0.26), yet these differences remained within a 10 HU range in most patients. No significant attenuation differences were found between CIart/VMI40keV in arterial vessels (p-range 0.06–0.86). Contrast-to-noise ratio provided by VMI40keV and CIart was equivalent for all arterial vessels assessed (p-range 0.14–0.91).Qualitatively, VMI40keV showed similar enhancement of abdominal and pelvic arteries as CIart and VNC were rated comparable to TNC.ConclusionOur study suggests that VNC and VMI40keV derived from single venous-phase SDCT offer comparable assessment of major abdominal vessels as provided by routine triphasic examinations, if no dynamic contrast information is required.

Unveiling coronary inflammation by perivascular fat angio-CT: a propensity-matched score analysis

Abstract Background Inflammation plays a pivotal role in the atherogenic process and recently has been the target of successful clinical trials. A new CT angiography method allows the identification of inflammatory pericoronary fat, which is associated with cardiovascular events. We aimed to determine whether patients with obstructive coronary artery disease (CAD) have a higher pericoronary inflammatory milieu when compared to those without CAD. Methods From a prospective CT angiography registry of patients with suspected obstructive CAD, those with a luminal stenosis &amp;gt;70% confirmed by invasive coronary angiography were screened (previous coronary artery bypass grafting was an exclusion criteria). Subsequently, we applied a 1:1 propensity score (PS) without replacement protocol to match obstructive CAD patients with those without CAD (non-CAD), using age, gender, BMI, hypertension, dyslipidemia, diabetes and smoking status as covariates. Similar to previous reports, pericoronary fat characterization by CT angiography was performed by analyzing the fat attenuation index (FAI) at the −30 to −190 HU range. Inflammatory fat was defined by a FAI &amp;gt;−70 HU. The proximal 50mm of the right coronary artery (RCA) was used to perform fat quantification and characterization. The perivascular fat was defined as the adipose tissue within a radial distance from the outer vessel wall equal to the diameter of the vessel. Results A matched cohort of 48 patients was identified (mean age 63 years; 77% males) – 24 obstructive CAD and 24 non-CAD patients. Mean FAI was numerically higher in obstructive CAD compared to the non-CAD cohort (−74±7 vs −78±7; p=0.083). Although not statistically significant, those with obstructive CAD had an increased proportion of inflammatory fat (51±10 vs 46±10%; p=0.107). After adjustment for body surface area (BSA), differences in the inflammatory fat proportion became apparent between obstructive CAD and non-CAD patients (28±6 vs 24±5%/m2; p=0.024). Furthermore, we observed a significant correlation between the inflammatory fat proportion (both absolute value and BSA adjusted) and the total number of RCA plaques (r=0.458; p=0.003; and r=0.451; p=0.003, respectively). Finally, there was 1 additional plaque observed in the RCA for each increase in 10% of proportion of inflammatory fat (p=0.018). Conclusions Perivascular coronary inflammation, as measured by FAI, seems significantly heightened in patients with obstructive CAD compared to a matched cohort of non-CAD patients. Further studies are needed to ascertain the mechanisms and possible implications of this association. Funding Acknowledgement Type of funding source: None

Dose perturbation caused by metallic port in breast tissue expander in proton beam therapy

Proton beam treatment is being looked favourably now in breast treatment. Tissue expanders are often placed after mastectomy that contains metallic port for saline injection which produces dose perturbations in proton beam therapy with uncertain dosimetry. Dose perturbation for a stainless-steel injection port from a breast implant is investigated in this study. Measurements, Monte-Carlo simulation, and calculated dose distribution of plans based on kVCT and MVCT images are compared. Treatment plans are performed on kVCT and MVCT images to observe the effect of metal artifact from the breast implant. The kVCT based plan underestimates the beam range due to the overestimated water equivalent thickness of the metal ports as a result of image degradation. Compared to the measurement with metal port in the proton beam, the MVCT-based treatment planning provides more accurate dose calculation than the kVCT-based results. The dose perturbation factor calculated from MVCT planning is within 10% of the measurement results while HU corrected kVCT plan still shows dose difference as large as 100% due to the incorrect range pull back calculation caused by the misrepresentation of the volume between the plastic cap and the stainless-steel base. The dose enhancement observed at the metal and solid water interface is as large as 15%, which needs to be accounted for in the planning process if there is a clinical concern. Dose reduction as large as 16% is observed with depth from 1 cm to 4 cm underneath the thickest part of the metallic port whereas lateral dose perturbation is also seen up to 7 mm. The measurement data are supported by the Monte-Carlo simulated results with a maximum dose difference of 6%. It is concluded that if proton beam is used with metallic port, MVCT imaging data is recommended. In lieu of MVCT, DECT, CT scanner with metal artifact reduction software or in the very least, extended HU range should be used to reduce the streaking artifact as well as to produce a more accurate image of the metallic port.

3:09 PM Abstract No. 248 Bone density changes after transjugular intrahepatic portosystemic shunt creation in patients with cirrhosis

To explore changes in bone density after transjugular intrahepatic portosystemic shunt (TIPS) creation in patients with cirrhosis. Among patients with cirrhosis undergoing TIPS creation between June 2003–January 2019 (n = 503) those with available non-contrast abdominal computed tomography during 1 month before and 6 months after TIPS were selected (n = 29). After exclusion of 2 cases due to TIPS thrombosis during 6 months, data regarding 27 subjects were analyzed. Axial L1 –L4 vertebral body CT density value was measured at 5 levels (mid-body, adjacent to the epiphyseal plates and midlines between mid-body and epiphyseal plate) using free-hand region of interest selection technique. CT density values (Hounsfield Unit) were averaged for each vertebra and per patient. Baseline and post-TIPS values were compared using the repeated measures analysis of variance (rANOVA). Cox regression analysis was used to evaluate association of post-TIPS bone density changes with overall survival. The primary indications for TIPS included refractory ascites (81.5%) or variceal bleeding (18.5%). Median bone density at baseline was 128.1 HU (range, 70.3 – 316.7) with a median post-TIPS change of 3.3 (range, -19.8 – 35.5) [median 102.2% (range, 79.7 – 124.9%) compared to baseline]. There was no statistically significant trend for bone Hounsfield Unit values after TIPS compared to baseline neither in overall analysis (P = 0.216) nor after splitting by TIPS indication (P = 0.263 and 0.656 for fluid overload and variceal bleeding, respectively). Also, there was no statistically significant association between pre-TIPS bone density (1.00, P = 0.993), post-TIPS absolute changes in HU values (HR: 0.98, P = 0.402) or relative changes to the baseline HU (HR: 0.98, P = 0.471) and post-TIPS overall survival. Osteoporosis is common in cirrhosis. TIPS creation can reverse cirrhosis-related muscle wasting. However, bone density does not change during 6 months after TIPS creation. Therefore the patients can still be in risk of fractures despite gaining muscle strength. More observations with longer follow-ups would further reveal any potential association.