Pelvic Scan Research Articles

Are Diagnostic Computed Tomography Chest Scans Sufficient for Detecting Supraclavicular in Initial Breast Cancer Staging?

<h3>Purpose/Objective(s)</h3> Initial staging workup strategies for locally advanced or suspected stage IV breast cancer can include computed tomography (CT) of the chest, abdomen, pelvis (CAP) and bone scan or, alternatively, a whole-body positron emission tomography/computed tomography (PET/CT). Variations in intravenous contrast injection site and bolus timing, arm positioning, and acquisition techniques on a CT chest scan could limit visualization of supraclavicular (SCV) and supracricoid cervical lymph nodes, which are critical for staging, prognosis, and treatment recommendations. The study's purpose is to determine whether there is a difference between the incidences of SCV and cervical lymphadenopathy detected on staging CT CAP versus PET/CT scans. <h3>Materials/Methods</h3> The records of consecutive newly diagnosed breast cancer patients who received initial staging scans at a single institution from 2012 to 2017 were reviewed in a HIPAA compliant, institutional review board-approved study. De-identified information was reviewed for inclusion: new breast cancer diagnosis, >18 years old, and availability of staging. Exclusion criteria were prior breast cancer treatment, re-staging for known recurrence, and nondiagnostic imaging examinations. Radiology reports were searched for SCV and cervical lymphadenopathy to determine the incidence detected by each imaging modality. A board certified neuroradiologist reviewed and characterized scans that noted cervical or SCV lymphadenopathy. <h3>Results</h3> The initial search resulted in 3,126 PET/CT and 631 CT CAP scans with 588 patients fulfilling the inclusion criteria. PET/CT scans had been performed in 539 patients and 49 received CT CAP and bone scans. The two groups were well matched by stage (Table 1). Metastatic cervical lymphadenopathy was detected by PET-CT in 50 patients (7.9%) versus two (3.7%) with CT CAP. Out of the 50 patients who had cervical lymphadenopathy detected by PET-CT, 30 (60%) had metastatic cervical lymphadenopathy above the level of the lung apex, the typical upper extent of a CT chest field of view. Although 25 (50%) patients had additional areas of distant metastatic disease, cervical lymphadenopathy above the thoracic inlet was the only site of distant metastasis for 13 patients (26%), and would not have been detectable by CT CAP. <h3>Conclusion</h3> PET/CT detected more cervical and SCV lymphadenopathy than CT CAP in initial staging scans for breast cancer, with 60% of those detected on PET/CTs in areas that would have been occult on standard CT chest scans. Such nodal involvement constituted the only site of distant metastatic disease in 26% of the patients. Thus, dedicated CT neck imaging may be a reasonable addition to CT CAP as an initial staging strategy to determine accurate staging and radiation treatment field volumes and borders.

Abdominal Aorto-Iliac Calcification Burden Assessment Using Deep Convolutional Neural Networks for Prediction of Cardiovascular Risk Among Prostate Cancer Patients Undergoing Stereotactic Body Radiotherapy (SBRT)

<h3>Purpose/Objective(s)</h3> Cardiovascular (CV) disease is among the leading causes of death for patients with prostate cancer. One novel strategy for automated screening for CV disease is the use of opportunistic imaging biomarkers derived from CT simulation scans. This study aims to investigate association of abdominal aorto-iliac calcification burden as measured qualitatively by physicians and quantitatively using a deep learning approach, and occurrence of major adverse CV events (MACE) among prostate cancer patients undergoing SBRT. <h3>Materials/Methods</h3> A retrospective study was conducted of 146 patients undergoing SBRT for localized prostate cancer (median age 68.9 years [interquartile range, IQR, 63.6-74.0]; 23.2% low risk, 35.1% intermediate risk, 11.6% high risk) between June 2007 and August 2018. MACE was collected from review of the medical chart, defined as a composite event of stroke, myocardial infarction, hospitalization for new onset heart failure, and CV death. Two physicians who were blinded to outcomes (WCC, JDB) independently reviewed non-contrast CT simulation scans to assess aorto-iliac calcification burden by a pre-defined 5-point scale (weighted Kappa: 0.72). Next, the abdominal aorta and common iliac arteries were contoured for 50 scans which served as a training dataset. A multi-stage UNet was trained to delineate aorto-iliac contours, achieving a mean dice score of 0.87±0.08 and Hausdorff distance of 1.9±0.6mm. Calcification burden was quantified using a per-voxel threshold of >130 Houndsfield units. <h3>Results</h3> 20 patients (13.7%) experienced MACE during a cohort-wide median clinical follow up of 5.9 years (IQR 4.7-6.4), and 5 patients (3.4%) died of CV disease and 10 patients (6.8%) of other causes (1 prostate cancer related). 49 patients (33.5%) had moderate to severe CaBS of 3 or higher. CaBS was significantly positively correlated with MACE in a dose dependent manner (P<0.0001, Cochran-Armitage test for trend), increasing from 6.2% for patients with mild/absent CaBS, to 20.6%, 37.5%, and 57.1%, for CaBS of 3, 4 and 5, respectively. Quantitative calcification burden (CaQ)derived from auto-segmentation was correlated with CaBS (Pearson r=0.79, P<0.0001) and achieved a similar area under the curve (AUC 0.74 vs 0.73 for CaBS) for MACE, resulting in a sensitivity of 78%, specificity of 63%, negative predictive value of 94.8%, and positive predictive value of 24.6%, using a cut-off of 1650 mm^3. Finally, both CaBS and CaQ remained significantly associated with MACE after adjusting for age on Cox regression (P=0.04, CaQ: HR 1.15 per 1000mm^3, 95% CI 1.005-1.33). <h3>Conclusion</h3> Abdominal aorto-iliac calcification burden was strongly associated with cardiovascular risk among patients undergoing SBRT for prostate cancer. A deep learning approach to quantify calcification burden on non-contrast pelvic CT simulation scans identified patients at elevated cardiovascular risk and may facilitate automated screening.

Usefulness of preoperative extracranial imaging in radiologically suspicious glioblastoma in the West of Scotland and proposal of an imaging diagnostic pathway.

A computed tomography chest, abdomen and pelvis scan (CT CAP) is probably unnecessary if a glioblastoma is detected on the initial CT brain (CTB) before more radiologically definitive magnetic resonance imaging (MRI). We audited its frequency to develop and improve our diagnostic management pathway. Twelve-month retrospective case series from 2018 of patients having an initial CTB suspicious for glioblastoma. We dichotomised patients into two groups: Group 1, tissue proven; and Group 2, non-tissue proven, owing to increased extracranial comorbidity in Group 2, which might influence a medical decision to request a CT CAP despite the radiological diagnosis of a glioblastoma being obvious on an initial CT. We quantified the frequencies of plain and contrast CTBs, CT CAPs and extracranial malignancy. In total, 131 patients had a CTB suspicious for glioblastoma; of these, 72% had a CT CAP and 17% had extracranial malignancy. In Group 1 (n = 84 [mean age 59 years]), 64% had a CT CAP. Plain CTB was undertaken in 24% of patients and contrast CTB in 76%. Extracranial malignancy was present in 8% and 12%. In Group 2 (n = 47 [mean age 73 years]), 85% had a CT CAP. Plain CTB was undertaken in 22% of patients and contrast CTB in 78%. Extracranial malignancy was present in 33% and 23%. Negative CT CAPs were found in ∼88% of CTBs in Group 1 and ∼75% of CTBs in Group 2. Patients having an initial contrast CTB suggestive of glioblastoma, prior to definitive MRI, who are going to be managed surgically, having no history of extracranial malignancy, do not necessarily need a CT CAP unless MRI is non-diagnostic.

Variations in size-specific effective dose with patient stature and beam width for kV cone beam CT imaging in radiotherapy

The facilities now available on linear accelerators for external beam radiotherapy enable radiation fields to be conformed to the shapes of tumours with a high level of precision. However, in order for the treatment delivered to take advantage of this, the patient must be positioned on the couch with the same degree of accuracy. Kilovoltage cone beam computed tomography systems are now incorporated into radiotherapy linear accelerators to allow imaging to be performed at the time of treatment, and image-guided radiation therapy is now standard in most radiotherapy departments throughout the world. However, because doses from imaging are much lower than therapy doses, less effort has been put into optimising radiological protection of imaging protocols. Standard imaging protocols supplied by the equipment vendor are often used with little adaptation to the stature of individual patients, and exposure factors and field sizes are frequently larger than necessary. In this study, the impact of using standard protocols for imaging anatomical phantoms of varying size from a library of 193 adult phantoms has been evaluated. Monte Carlo simulations were used to calculate doses for organs and tissues for each phantom, and results combined in terms of size-specific effective dose (SED). Values of SED from pelvic scans ranged from 11 mSv to 22 mSv for male phantoms and 8 mSv to 18 mSv for female phantoms, and for chest scans from 3.8 mSv to 7.6 mSv for male phantoms and 4.6 mSv to 9.5 mSv for female phantoms. Analysis of the results showed that if the same exposure parameters and field sizes are used, a person who is 5 cm shorter will receive a size SED that is 3%–10% greater, while a person who is 10 kg lighter will receive a dose that is 10%–14% greater compared with the average size.

Factors associated with caesarean section in women referred for preinduction - a nested case-control study in dinoprostone and misoprostol groups.

Induction of labour is a beneficial perinatal procedure, but may be associated with some risks. The aim of this study was to identify factors associated with the need for Caesarean section in women referred for preinduction with dinoprostone and misoprostol. It was a retrospective cohort study of 560 pregnant women who underwent labour induction for medical reasons. Analyses were performed separately in the dinoprostone and misoprostol group. Above other characteristics, the diameters of the pelvis and abdominal circumference of pregnant women were analysed. There were some mothers' characteristics like age, weight, BMI, presence of hypothyroidism or diabetes, which were not associated with Caesarean section deliveries. Women in the misoprostol group with gestational age less than 38 weeks had an increased risk of Caesarean section (OR 2.189; p = 0.041). The analyses of combined effect of mothers age and parity history showed 6.7 (in dinoprostone group) and over 10 times (in misoprostol group) increased the risk of Caesarean section in nulliparous women over 35 years of age. The increased risk of Caesarean delivery in the dinoprostone group was combined with the intertrochanteric dimensions such as the mother's height measuring less than 165 cm, nulliparity and hypertension. In the misoprostol group, strong risk factors for Caesarean delivery were mothers aged 35 years or more, gestational age less than 38 weeks and nulliparity and hypertension as in dinoprostone group. The oxytocin infusion had increased the risk of Caesarean section only in the combined dinoprostone and misoprostol group. Further high-quality studies are warranted.

Acute Pancreatitis Related to COVID-19 Infection: A Systematic Review and Analysis of Data.

There is increasing literature mentioning severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection (COVID-19 infection) causing acute pancreatitis (AP). It is hypothesized that SARS-Cov-2 causes pancreatic injury either by direct cytotoxic effect of the virus on pancreatic cells through the angiotensin-converting enzyme 2 (ACE2) receptors - the main receptors for the virus located on pancreatic cells - or by the cytokine storm that results from COVID-19 infection or a component of both. Many viruses are related to AP including mumps, coxsackievirus, cytomegalovirus (CMV), Epstein-Barr virus (EBV), and as data evolves SARS-CoV-2 virus may be one of them as well. We conducted a systematic literature review to explore the current literature and provide an overview of the evidence of AP in COVID-19 infection. We studied the presence of AP in patients with SARS-CoV-2 infection and calculated the time of diagnosis of SARS-CoV-2 infection with respect to the time of diagnosis of AP. We also studied the age, gender, clinical manifestations, time of onset of symptoms, laboratory values, imaging findings, mortality, length of stay, comorbidities, need for Intensive Care Unit (ICU) care, and excluded any other common causes of AP. We included 40 articles comprising 46 patients. All patients had a positive SARS-CoV-2 polymerase chain reaction (PCR) test and all patients had AP as per Atlanta’s criteria. The most common clinical presentation was abdominal pain in 29 (63.0%). Edematous pancreas was the most common Computed Tomography Abdomen Pelvis (CTAP) scan finding in these patients (35 patients). Seventeen (37%) patients required ICU admission and six (13%) patients died. Our study provides an important overview of the available data on AP in COVID-19 patients and concludes that AP is an important complication in COVID-19 infection and should be considered as an important differential in patients with COVID-19 infection who complain of abdominal pain.

SP9.1.3 Colorectal Cancer Referrals During COVID-19: The Use of CT and qFIT in Triaging Patients in NHS Grampian

Abstract Introduction The COVID-19 outbreak resulted in fundamental changes to clinical practice for patients referred to secondary care with lower gastrointestinal symptoms. The use of colonoscopy services was reduced due to a perceived risk of viral transmission. Resultantly, computed tomography abdomen pelvis (CTAP) scans were utilised to triage patients. This study aimed to assess the accuracy of CTAP and qFIT in triaging patients at risk of colorectal cancer. Methods This study retrospectively gathered data on patients referred via the urgent suspected cancer (USC) pathway from the start of lockdown over a 6-month period in a single Scottish Health Board. Data were collected on presenting symptoms, qFIT levels, vetting decision, investigations, and subsequent diagnosis. Patients were vetted into one of five pathways: CTAP, direct to colonoscopy, downgraded from assessment, flexible sigmoidoscopy, or CT colonography. Results The overall cancer detection rate was 6.4%. Of the patients with cancer on the CTAP pathway, 22.9% had cancer undetected on CTAP which was later identified on colonoscopy. In the cohort of patients with colorectal malignancy, 7.5% had a negative qFIT value (&amp;lt;10 ug/g). Conclusion CTAP alone may not be accurate in detecting colorectal cancers. One should consider the whole clinical picture and decide whether further imaging is warranted following a negative CTAP scan. Additionally, qFIT remains the leading laboratory investigation within screening programmes, however, it should not be used in isolation to rule out colorectal malignancy.

Intestinal-type adenocarcinoma presenting as a female periurethral mass

BackgroundThe periurethral mass in the female is a rare clinical entity and most of the lesions are benign. We present an unusual case of a periurethral mass found to be intestinal-type adenocarcinoma which has not been previously reported in the literature.Case presentationA 58-year-old woman was referred to our hospital with acute urinary retention. She complained of frequency, urgency and progressive obstructive urinary symptoms for the last 3 months. A pelvic magnetic resonance imaging scan showed a soft tissue mass of 5 × 4 cm surrounding the entire urethra. A needle biopsy was done and revealed adenocarcinoma with intestinal-type features. The tumor was removed by a simultaneous laparoscopic abdominal and transperineal approach. The pathological results showed a positive surgical margin and urethra and vagina wall invasion. The neoplastic cells were positive for CK20, CDX-2, CerbB-2, MSH2, MSH6, MLH1, PMS2 and P53. The patient received adjuvant systemic chemotherapy comprising S-1 and oxaliplatin. Follow-up with pelvic MRI 6 months after surgery showed no signs of local recurrence.ConclusionsWe have reported the first case of the primary periurethral adenocarcinoma of intestinal type. There are currently no standardized protocols for the diagnosis, clinical course, and treatment of this rare tumor. This case study can aid decision-making regarding the diagnosis and treatment of this tumor.

Computed Tomography and Patient Risk: Facts, Perceptions and Uncertainties

Aim: To assess the role of computed tomography for management of Covid-19. Study design: Prospective study Place and duration of study: Department of Radiology, Ghulam Muhammad Mahar Medical College Teaching Hospital Sukkur from 1st November 2020 to 31st December 2021. Methodology: One hundred cases within various ages 5-55 years for analyzing their risk for CT scanning on them by highlighting the facts related to CT scan, patient perceptions and uncertainties regarding it. A 50 radiologist and 50 emergency doctors were also asked questions regarding their knowledge about CT scan risks and their responses were also documented. However previous CT record of patients suffering from carcinoma was also analyzed for understanding the fact related with CT imaging. Results: The mean age of patients undergoing CT scan was 39.5±5.6 years. There were 55% males who underwent CT scans while 45% females. The usual dosage for various radiological procedure shows that highest dose deliverance was given to the patients of CT pulmonary angiogram and coronary angiography. Only 50% of radiologists knew that CT scan is associated with high risk of malignancies. There were only 10% emergency medical doctors who also knew CT imaging relation with malignancy risk. Only 54% patients considered abdomen pelvic scan to be associated with increasing lifetime risk of cancer while 23% of the patients considered chest scan to be associated with escalating the risk of cancer. Conclusion: Computed tomography scan is related with a high risk of radiation exposure. There is a dire need of perception development and risk understanding with medical professionals and general public for minimizing this risk. Key words: Computed tomography, Risk, Facts, Perception, Uncertainties

Posterior wall fractures of the acetabulum: treatment using an anatomical plate through direct posterior approach.

This study was aimed to measure the application of W-shaped acetabular angular plate (WAAP) through direct posterior approach (DPA) on the reconstruction of acetabular posterior wall fractures when compared with reconstruction plates. A retrospective study was performed on patients treated with the WAAP or reconstruction plates via the DPA. The intraoperative data of operative time, blood loss and radiation exposure times were recorded. Radiographs of the pelvis and CT scan were obtained within one week post-operation to assess the reduction quality. The clinical outcome was evaluated by the modified Merle d'Aubigne and Postel score. From May 2016 to October 2019, a total of 41 patients with simple acetabular posterior wall fractures were included in this study, 22 from the WAAP group and 19 from the reconstruction plates group. There were no significant differences between the two group in age, gender, time from injury to operation, cause of injuries, length of incision and follow-up time (P > 0.05). In comparison with the reconstruction plates group, the average operation time of the WAAP group was significantly shorter (46.1 ± 12.7min vs 59.2 ± 17.4min, P < 0.05), the average radiation exposure times were significantly less (2.3 ± 0.6 vs 3.6 ± 1.0, P < 0.001), the average blood loss was significantly less (240 ± 98.9ml vs 301.1 ± 66.6ml, P < 0.05). According to Matta radiology criteria and the modified Merle d' Aubigne and Postel score, no significant difference was observed between the two group, as for the quality of reduction and function outcomes. The application of WAAP through DPA showed satisfactory preliminary clinical outcomes, showing promise to be an alternative technique for the treatment of acetabular posterior wall fractures.

Three-Dimensional in Vivo Anatomical Study of Female Iliac Vein Variations

Objective To investigate female iliac vein variations by using the computed tomography angiography (CTA) three-dimensional (3 D) reconstruction technique. Methods We retrospectively studied 1623 patients undergoing abdominal and pelvic CTA scanning for gynecological diseases from December 2009 to December 2018. Accurate digital 3 D models of the iliac vein were constructed using Mimics 19.0 software and used to study the morphology and variations. Variations in the common iliac vein (CIV), external iliac vein (EIV) and internal iliac vein (IIV) were classified as type I, abnormal number of veins; type II, abnormal communicating branches; or type III, other variations. Results The overall variation rates of the iliac vein and CIV were 51.57% (837/1623) and 20.33% (330/1623), respectively. The main type of CIV variation was type II. The main type I CIV variation was the absence of the CIV (98.15%), which mostly occurred on the right side (64.81%, 35/54). Type II CIV variation was the most common, with abnormal communicating branches between the left CIV and right IIV (81.78%, 211/258). The overall variation rates of the EIV and IIV were 36.66% (595/1623) and 49.60% (805/1623), respectively, mainly on the right side. The main type of variation was type I. Among them, the division of the IIV into two branches plus convergence with the ipsilateral EIV was the most common (22.98%, 373/1623). Conclusion In this study, approximately half of the patients had iliac vein variations. The preoperative identification of iliac vein variation may reduce vascular injury in pelvic surgery.

Alignment of the Cervix with the Vagina in Uterine Retroversion: A Possible Risk Factor in Uterine Prolapse.

Multiple observational studies have found an association of uterine prolapse with uterine retroversion. Mechanisms proposed to explain this apparent association assume that the cervix of a retroverted uterus will usually insert at the apex of the vagina, with resultant alignment of the cervix with the vagina. The angle of the axis of the cervix with the axis of the vagina was measured by two readers on 323 sagittal pelvic MRI scans and sagittal reconstructions of pelvic CT scans performed for clinical purposes. One reader observed and recorded the anatomic relations of the uterus that differed by insertion site and version: 44 of 49 retroverted uteri (89.8%) inserted at the vaginal apex, and 13 of 274 anteverted uteri (4.7%) inserted at the vaginal apex. This difference was found to be statistically significant (p < 0.05) by the Chi square test. The urinary bladder, vaginal walls, and rectum were inferiorly related to anteriorly inserted anteverted uteri. Only the vaginal lumen and the rectum at a shallow oblique angle were inferiorly related to apically inserted retroverted uteri. Most retroverted uteri insert at the apex of the vagina. Apically inserted retroverted uteri appear to receive less support from adjacent structures than anteriorly inserted anteverted uteri.

Association of preoperative Enzian score with postoperative fertility in patients with deep pelvic endometriosis

IntroductionEndometriosis is a chronic inflammatory disease with a negative impact on fertility. The Enzian classification provides a precise description of deep pelvic endometriotic lesions, especially in the retroperitoneal area, from preoperative pelvic MRI scans. However, it is not known if it is correlated with postoperative fertility. Study objectiveTo determine if there is an association between the preoperative Enzian score and postoperative fertility after deep pelvic endometriosis surgery. DesignWe conducted a descriptive, retrospective study using information from the ENDOREN database. SettingThis was a retrospective study at the Department of Obstetrics and Gynecology at Rennes University Hospital (France) from January 2013 to May 2019 Patients and interventionsWe used information from the ENDOREN database that included all women who underwent surgery for deep endometriosis and wish to conceive. This surgery was intended in a view to achieve a complete removal of endometriosis. MeasurementsThe Enzian score was calculated from preoperative MRI scans, and total, spontaneous, and after In Vitro fertilization (IVF) live births and pregnancies outcomes were collected from the patients'computerized medical records. Univariate and multivariate analysis was performed. ResultsSixty-eight patients were included. The live-birth rate was 35% (24/68). According to the Enzian classification, 25 patients (35%) were classified in compartment A, 64 patients (94%) in compartment B, and 27 (40%) in compartment C. In multivariate analysis, positive predictor of live birth was single Enzian B score (OR=4.7[1.21; 18.81], p = 0.03), negative predictors were uterine adenomyosis and a history of endometriosis surgery. In multivariate analysis, positive predictor of spontaneous live birth was EFI score ≥7 (OR =22.434; CI [1.138; 442.190]). In multivariate analysis, positive predictor was Enzian A score (OR=15.9[2.2; 114.7], p = 0.006), and negative predictors was uterine adenomyosis and Enzian B score (OR=0.01[0; 0.495], p = 0.02) for live birth after IVF. ConclusionThe present retrospective study cannot strongly conclude about fertility and correlation with Enzian score because the groups are too small. However, it seems that when solely the compartment B is involved by endometriosis, complete full removal of endometriosis leads to better post-operative live births results. Other studies must be done to determine if Enzian classification based on preoperative pelvic MRI could be clinical value in the decision-making strategy for managing infertile patients with deep pelvic endometriosis.

Pelvic Pyomyositis in Childhood: Clinical and Radiological Findings in a Tertiary Pediatric Center.

Pyomyositis (PM) is an infrequent but increasing bacterial infection of the skeletal muscle, with muscles of the pelvis and thigh frequently involved. The diagnosis is often challenging, especially when a deep muscle is affected. We present a single-center pediatric cohort affected by pelvic PM. A retrospective analysis was performed, including children admitted to Meyer Children’s Hospital between 2010 and 2020. Demographic, anamnestic, clinical, laboratory, radiological and management data were collected. Forty-seven patients (range 8 days–16.5 years, 66% males) were selected. Pain (64%), functional limitations (40%) and fever (38%) were the most common presenting symptoms; 11% developed sepsis. The median time to reach the diagnosis was 5 days (IQR 3–9). Staphylococcus aureus was the most common organism (30%), Methicillin-Resistant S aureus (MRSA) in 14%. PM was associated with osteomyelitis (17%), arthritis (19%) or both (45%). The infection was multifocal in 87% of children and determined abscesses in 44% (40% multiple). Pelvic MRI scan, including diffusion-weighted imaging (DWI), always showed abnormalities when performed. Clinical and laboratory findings in pelvic PM are unspecific, especially in infancy. Nevertheless, the infection may be severe, and the suspicion should be higher. MRI is the most useful radiological technique, and DWI sequence could reveal insidious infections.

Empirical scatter correction: CBCT scatter artifact reduction without prior information.

The image quality of cone beam CT (CBCT) scans severely suffers from scattered radiation if no countermeasures are taken. Scatter artifacts may induce cupping and streak artifacts and lead to a reduced image contrast and wrong CT values of the reconstructed volumes. Established software-based approaches for a correction of scattered radiation typically rely on prior knowledge of the CT system, scan parameters, the scanned object, or all of theaforementioned. This study proposes a simple and effective postprocessing software-based correction method of scatter artifacts in CBCT scans without specific priorknowledge. We propose the empirical scatter correction (ESC), which generates scatter-like basis images from each projection image by convolution operations. A linear combination of these basis images is subtracted from the original projection image. The logarithm is taken and an FDK reconstruction is performed. The coefficients needed for the linear combination are determined automatically by a downhill simplex algorithm such that the resulting reconstructed images show no scatter artifacts. We demonstrate the potential of ESC by correcting simulated volumes with Monte Carlo scatter artifacts, a head phantom scan performed on our table-top CBCT, and a pelvis scan from a Varian Edge CBCTscanner. ESC is able to improve the image quality of CBCT scans, which is shown on the basis of our simulations and on measured data. For a simulated head CT, the CT value difference to the scatter-free reference image was as low as -6 HU after using ESC, whereas the uncorrected data deviated by more than -200 HU from the reference data. Simulations of thorax and abdomen CT scans show that although scatter artifacts are not fully removed, anatomical features which were hard to discover prior to the correction become clearly visible and better segmentable with ESC. Similar results are obtained in the phantom measurement, where a comparison to a slit scan of our head phantom shows only small differences. The CT values in soft tissue are improved in this measurement, as well. In soft tissue areas with severe scatter artifacts, the CT values agree well with those of the slit scan (difference to slit scan: 35HU corrected and -289 HU uncorrected). Scatter artifacts in measured patient data can also be reduced using the proposed ESC. The results are comparable to those achieved with designated correction algorithms installed on the Varian Edge CBCT system. ESC allows to reduce artifacts caused by patient scatter solely based on the projectiondata.

Automated Femoral Landmark Detection from Pelvic X-Rays

Surgical planning requires the identification of anatomical landmarks on medical images pre, intra, and post-procedures. Landmark detection on X-rays is thus an important, though time intensive, step to ensure good surgical outcomes. The operative workflow can be made more efficient by using machine learning approaches to automate the detection of landmarks. These models could also assist with the development of robotic surgical procedures, as robotic approaches to surgery require the robotic device to orient itself to the patient's anatomy. Previously described models are effective, but complex, making it difficult for landmark identification to occur in real-time in a robotic system. We propose a streamlined approach to landmark detection on pelvis radiographs that achieves similar accuracy to gold-standard manual annotations. To train and evaluate the network, 902 pelvic radiographs (382 Outlet view, 520 AP view) were annotated with 22 landmarks and split into training (n = 700), validation (n = 99), and testing (n = 103) set. A U-Net architecture with five encoding layers and five decoding layers was used. Landmark labels were converted into 128 × 128 × 22 heatmap array by placing a Gaussian blur filter (5% of image size) over each landmark in order to generate a single 128 × 128 layer of the array, thus generating the 22 layers of the overall heatmap array with one landmark heatmap on each layer. Each layer was an array of 0 except a circular Gaussian around the area of the landmark. A 256 × 256 array representing the image was fed into the U-Net architecture, which outputted a 128 × 128 × 22 heatmap array. Intersection over union loss was used to train the network. Following training for 100 epochs, the algorithm was able to predict the position of 22 clinically relevant landmarks with an average error of 2.36±.5 mm compared to ground-truth annotations made by trained experts and musculoskeletal radiologists with experience in pelvic scan analysis. The network was able to accurately determine the position of relevant landmarks. It was able to do this despite highly variable contrast and brightness in the dataset. Prediction accuracy was invariant to view (AP: 2.27±.51 mm, Outlet: 2.45±.64 mm). A prediction took 1.13±.07 seconds. The network is able to rapidly provide accurate femoral landmarks on a radiograph of the pelvis. This will allow for the automation of numerous clinically relevant measurements. Additionally, an important avenue of further research is exploring whether automated use of these measurements can aid in the prediction of femur fractures in machine learning models.

Role of Perirectal Fat in the Carcinogenesis and Development of Early-Onset Rectal Cancer.

Purpose The incidence of early-onset rectal cancer (EORC) has been increasing since the past decade, while its underlying cause remained unknown. This study was aimed at clarifying the relationship between perirectal fat area (PFA) and EORC. Patients and Methods. All patients with rectal cancer who received radical excision between January 2016 and December 2017 at our hospital were included. The fat series images of pelvic magnetic resonance imaging scans were obtained and PFA at the ischial spine level was calculated using the ImageJ software. Results A total of 303 patients were finally included and divided into two groups according to the median PFA: Group 1 (<20.2 cm2, n = 151) and Group 2 (≥20.2 cm2, n = 152). PFA positively correlated with body weight and body mass index. PFA increased with invasion depth, lymph node metastasis, TNM stage, tumor deposits, and vascular invasion. Patients with EORC had higher PFA than those with late-onset rectal cancer (LORC; P = 0.009). Among patients with stage I–III rectal cancers, those in Group 2 had significantly shorter disease-free survival (P = 0.010) and overall survival (P = 0.034) than those in Group 1, and PFA was an independent predictor of disease-free survival (OR: 1.683 [1.126-3.015], P = 0.035) and overall survival (OR: 1.678 [1.022-2.639], P = 0.046). Conclusions Patients with EORC had significantly higher PFA than those with LORC. PFA is positively correlated with T stage, N stage, TNM stage, tumor deposit, and vascular invasion and is an independent predictor of disease-free survival and overall survival. Therefore, perirectal fat may be involved in the carcinogenesis and development of EORC.

Abstract OT2-24-03: Phase II study of a PARP inhibitor in metastatic breast cancer with somaticBRCA1/2mutations identified by cell-free DNA: Genotyping based clinical trial

Abstract Background: Two PARP inhibitors are approved for germline BRCA1/2 mutant metastatic breast cancer (MBC), based on clinical trials demonstrating an improvement in patient outcomes and quality of life. However, germline BRCA1/2 mutations are identified in 5-10% of breast cancer, limiting their potential applicability. Our prior work demonstrated that somatic BRCA1/2 mutations can be detected in cell-free DNA (cfDNA) in a proportion of patients with MBC who are not germline BRCA1/2 carriers, and that a PARP inhibitor caused growth inhibition in a circulating tumor cell line generated from a patient with MBC and a pathogenic somatic BRCA1 mutation (Vidula, Dubash, CCR, 2020). Thus, we hypothesize that a PARP inhibitor may have efficacy in somatic BRCA1/2 mutant MBC identified by cfDNA. Trial Design: This phase II investigator initiated open label clinical trial is enrolling 30 patients who have pathogenic somatic BRCA1/2 mutations found in cfDNA. Patients must not be known germline BRCA1/2 carriers. Patients receive treatment with the PARP inhibitor, talazoparib, until disease progression. Serial imaging (CT chest, abdomen, pelvis, and bone scan) occurs every 3 months, and cfDNA is collected monthly to evaluate changes in the genomic environment. Patients will also have blood collected at baseline for the Cancer Risk B assay (CR-B), a novel flow variant assay to assess double strand break repair mutations in circulating blood cells (Syeda, Genetics, 2017). Eligibility criteria: Patients with MBC (TNBC with ≥ 1 prior chemotherapy or HR+/HER2- with ≥ 1 prior hormone therapy or ineligible for hormone therapy) with a somatic BRCA1/2 mutation identified in cfDNA (established pathogenic variant) are being enrolled. Patients should not be known germline BRCA1/2 carriers (genetic testing is not required but can be obtained per physician discretion) and may not have previously received a PARP inhibitor. There is no limit on the number of prior therapies, and a prior platinum chemotherapy is allowed in the absence of disease progression on the platinum. Patients must have adequate performance status and organ function. Specific Aims: The primary endpoint is progression-free survival (PFS) using RECIST 1.1. Secondary endpoints include objective response rate and toxicity (NCI CTCAE v 5.0). Exploratory objectives include evaluating serial changes in BRCA1/2 mutant allelic frequency in cfDNA, evaluating the impact of BRCA1/2 reversion mutations, comparing pre- and post-treatment cfDNA results to identify markers of resistance, evaluating the CR-B assay positivity rate, and ultimately correlating these analyses with treatment response. Statistical Methods: A two-stage design with 80% power to demonstrate that talazoparib is associated with “success” (PFS &amp;gt; 12 weeks) in ≥53% patients (4% alpha) is being used. Accrual: This study (NCT03990896) is currently open at Massachusetts General Hospital, where 4 patients are completing screening for enrollment. This study will be activated soon at the University of California San Francisco, MD Anderson, Mayo Clinic Rochester and Jacksonville, Northwestern, and Emory (7 academic centers). Funding: Support for this study is provided by a Pfizer ASPIRE award and Conquer Cancer Foundation of ASCO–Breast Cancer Research Foundation- Career Development Award. Contact information: Neelima Vidula, MD, Massachusetts General Hospital, nvidula@mgh.harvard.edu Citation Format: Neelima Vidula, Erica Blouch, Erin Basile, Nathan Royce Ruffle-Deignan, Nora Horick, Senthil Damodaran, Alvaro Moreno Aspitia, Manali Bhave, Ami Shah, Minetta C. Liu, Joseph Sparano, Harry Ostrer, Hope Rugo, Leif W. Ellisen, Aditya Bardia. Phase II study of a PARP inhibitor in metastatic breast cancer with somaticBRCA1/2mutations identified by cell-free DNA: Genotyping based clinical trial [abstract]. In: Proceedings of the 2021 San Antonio Breast Cancer Symposium; 2021 Dec 7-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2022;82(4 Suppl):Abstract nr OT2-24-03.

Abstract OT1-18-08: Randomized phase II trial of pembrolizumab/carboplatin vs. carboplatin alone for breast cancer with chest wall recurrence: TBCRC044

Abstract Background: A significant number of patients with breast cancer may develop chest wall recurrence, which can be difficult to treat, and is associated with a poor prognosis. Given the inflammatory nature of chest wall disease, and the association of chest wall disease with lymphovascular invasion, we hypothesized that immunotherapy may be beneficial in this setting. Furthermore, combining immunotherapy and chemotherapy may have a synergistic effect; indeed, the combination of the anti-programmed cell death 1 (PD-1) antibody, pembrolizumab, with chemotherapy has been approved for metastatic triple negative breast cancer (TNBC). Consequently, in this study, we are evaluating the combination of pembrolizumab/carboplatin vs. carboplatin alone for chest wall recurrence. Trial design: This is a phase II study of patients with chest wall disease from breast cancer. Patients are randomized in a 2:1 manner to pembrolizumab/carboplatin x 6 cycles (Arm A) with the option to continue pembrolizumab +/- carboplatin after 6 cycles (Arm Ax) vs. carboplatin alone (Arm B) with the option to cross-over to pembrolizumab +/- carboplatin on progression (Arm Bx). Carboplatin is dosed at AUC 5 IV every 3 weeks, and pembrolizumab at 200 mg IV every 3 weeks. Trastuzumab may be continued with study treatment in patients with HER2 positive disease. Imaging scans (CT chest, abdomen, and pelvis, and bone scan) occur at baseline and every 3 cycles. Chest wall biopsies and peripheral blood is collected at baseline and after completing 2 cycles of treatment for correlative studies. Eligibility criteria: Patients must have chest wall disease from breast cancer. Distant metastases are allowed. TNBC, hormone receptor positive/HER2 negative disease (after 2 prior hormone therapies), and HER2 positive disease (progressed on standard HER2 directed treatment) are eligible. Any number of prior lines of chemotherapy are acceptable, including a prior platinum chemotherapy in the absence of disease progression on the platinum. Specific Aims: Primary aim is to determine disease control rate in the chest wall and other distant sites at 18 weeks of treatment with RECIST 1.1. Secondary aims including determining toxicity, progression-free survival, response based on irRECIST, and response based on tumor PD-L1 expression. Exploratory aims include studying changes in: 1) immune composition of tumor and peripheral blood, 2) peripheral blood cell-free DNA and circulating tumor cells, 3) soluble PD-L1 expression, and 4) association of MYC with PD-1 and immune markers, based on preclinical data demonstrating that MYC upregulates these markers. Statistical Methods: 84 patients (Arm A: 56, Arm B: 28) are being enrolled at 7 sites in the Translational Breast Cancer Research Consortium. The study is powered to identify a 20% difference in disease control rates between Arms A and B (HR 0.52, α= 0.10, ß=0.20). A futility analysis will occur for Arm B after 18 patients are enrolled to allow for early closure if lack of efficacy. Accrual: Present accrual is 57 patients (Arm A: 39, Arm B: 18). (NCT03095352). This trial is partly funded by grants from Merck and University of California San Francisco. Contact information: Neelima Vidula, MD, Massachusetts General Hospital, nvidula@mgh.harvard.edu Citation Format: Neelima Vidula, Rita Nanda, Kathy Miller, Leisha Emens, Vandana Abramson, Ben Park, Minetta C. Liu, Andrei Goga, Hope Rugo. Randomized phase II trial of pembrolizumab/carboplatin vs. carboplatin alone for breast cancer with chest wall recurrence: TBCRC044 [abstract]. In: Proceedings of the 2021 San Antonio Breast Cancer Symposium; 2021 Dec 7-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2022;82(4 Suppl):Abstract nr OT1-18-08.

Clinical aspects of oocyte retrieval and embryo transfer: tips and tricks for the novice and the expert.

Oocyte retrieval (ovum pick-up) and embryo transfer (ET) are essential steps in in-vitro fertilization and intracytoplasmic sperm injection and over the years, the two procedures were developed in order to improve the clinical outcome. Many suggestions were proposed and applied before, during and after oocyte retrieval such as timing of HCG trigger, pre-operative pelvic scan, vaginal cleansing, type of anesthesia, type and gauge of aspiration needles, aspiration pressure, follicle flushing, and the need for prophylactic antibiotics. Similarly, many steps were suggested and implemented before, during and after ET including patient's position, type of anesthesia/analgesia, dummy (mock) ET, ultrasound-guidance, HCG injection in the uterine cavity, use of relaxing agents, full bladder, removal of the cervical mucus, flushing the cervix with culture medium, type of ET catheter, embryo loading techniques, site of embryo deposition, the use of adherence compounds, as well as bed rest after ET. Complications were also reported with oocyte retrieval and ET. The aim of this review is to evaluate the current practice of these two procedures in the light of available evidence.