The coronavirus disease 2019 (COVID-19) pandemic resulted in widespread disruption to the global economy, including demand for imaging services. The resulting reduction in demand for imaging services had an abrupt and substantial impact on private radiology practices, which are heavily dependent on examination volumes for practice revenues. The goal of this report is to describe the specific experiences of radiologists working in various types of private radiology practices during the initial peak of the COVID-19 pandemic. Herein, the authors describe factors determining the impact of the pandemic on private practices, the challenges these practices faced, the cost levers leaders adjusted, and the government subsidies sought. In addition, the authors describe adjustments practices are making to their mid- and long-term strategic plans to pivot for long-term success while managing the COVID-19 pandemic. Private practices have crafted tiered strategies to respond to the impact of the pandemic by pulling various cost levers to adjust service availability, staffing, compensation, benefits, time off, and expense reductions. In addition, they have sought additional revenues, within the boundaries of their practice, to mitigate ongoing financial losses. The longer term impact of the pandemic will alter existing practices, making some of them more likely than others to succeed in the years ahead. This report synthesizes the collective experience of private-practice radiologists shared with members of the Radiological Society of North America COVID-19 Task Force, including discussions with colleagues and leaders of private-practice radiology groups from across the United States.

e14572 Background: Objective response rates (ORR) utilizing RECIST or WHO criteria have been traditionally used as clinical endpoints to assess efficacy of cytotoxic chemotherapy. However in the era of immunotherapeutic agents, response rate assessment can be misleading due to nonconventional responses resulting in premature discontinuation of treatment. Wolchok et al proposed immune-related response criteria (irRC) to assess immune responses in melanoma. He also noted that stable disease which is not indicative of antitumor activity could be a potential surrogate marker of better clinical outcome. Brahmer et al reported nonconventional pattern of responses with Nivolumab in lung cancer. Methods: A retrospective chart review was done to assess differences in responses utilizing both RECIST v1.1 and irRC criteria in lung cancer patients treated with Nivolumab. Patients who received minimum of 4 cycles of Nivolumab were included in the study. The CT scans were reviewed by a senior radiologist. We reviewed 64 patients treated with Nivolumab between 4/30/2015 to 6/21/2016 and 30 patients were found eligible. Results: Patient characteristics. Male 53%; median age 61 years; squamous 47%; adeno 40%; small cell 13%; Median cycles of Nivolumab 6. Response rates utilizing both criteria was essentially similar with only 2 patients showing dis-concordant responses (6.6%). We utilized RECIST responses criteria for further analysis. Partial response (PR) 2/30; stable disease (SD) 12/30; progressive disease (PD) 15/30 and not evaluable (NE) 1/30. ORR 6.6%. Kaplan–Meier curve was used to analyze difference in survival between patients with PR+SD and PD. The median survival for PD was 9 months and PR+SD was not reached at median follow up of 1 year. Overall survival at 1 year for PD 33% and PR+SD 60% (p = 0.048). Hazard ratio for PD was 3.060 (p = 0.60). Conclusions: Patients with stable disease had a better survival and should be considered as responders though traditionally not included in the ORR. However irRC did not help in differentiating nonconventional immune responses in lung cancer patients. [Table: see text]

Reade, Clifton C. MD; Jenkins, Nelson L. MD; Bard, Michael R. MD, FACS; Kuszyk, Brian S. MD; Koutlas, Theodore C. MD, FACS; Rotondo, Michael F. MD, FACS Author Information

Study Design. A cross-sectional age- and sex-matched study comparing the prevalence and size of dural ectasia in two groups of patients with Marfan syndrome. Group I comprised patients with moderate to severe back pain and Group II comprised patients without back pain. Objectives. To determine whether the presence and size of dural ectasia is associated with back pain in patients with Marfan syndrome. Summary of Background Data. Dural ectasia is present in more than 60% of patients with Marfan syndrome. Moderate to severe back pain is present in more than 50% of patients with Marfan syndrome. Most cases of significant low back pain in patients with Marfan syndrome do not have a clear cause. It would be useful for the clinician to know whether dural ectasia may be a cause of back pain in patients with Marfan syndrome with no other source. Methods. Thirty two volunteers aged 30–50 with Marfan syndrome were enrolled as age- and sex-matched pairs with significant back pain (Group I) and without back pain (Group II). A completed questionnaire, physical examination, and magnetic resonance image of the lumbosacral spine were obtained. Dural volume caudal to L5 was calculated from the magnetic resonance data by specially designed software. Results. Dural ectasia was present in 76% of the patients in Group I, and 41% of the patients in Group II. The proportion of patients with dural ectasia was significantly higher in Group I. Furthermore, the mean dural volume was significantly higher in Group I, and a significant correlation between dural volume and Oswestry pain score was noted. Conclusions. The presence and size of dural ectasia are associated with back pain in the Marfan syndrome. However, a high prevalence of dural ectasia (41%) exists even in patients with Marfan syndrome without back pain. The mere presence of dural ectasia therefore does not necessarily mean the patient will be symptomatic even though the two are associated.

OBJECTIVE:The purpose of this study was to evaluate the effect of lesion enhancement on the conspicuity of small hypovascular hepatic tumors in an animal model.MATERIALS AND METHODS:Seven VX2 hepatic tumors in five rabbits were imaged. Dynamic contrast-enhanced CT was performed at a single level centered over the lesions at 5-sec intervals for 119 sec after injection of 2 ml/kg i.v. contrast material at 2 ml/sec. Attenuation was measured over time within regions of interest in the tumor and normal liver, aorta, inferior vena cava, and portal vein. Lesion conspicuity, defined as the difference between the attenuation of the uninvolved liver and neoplasm, was calculated.RESULTS:The mean diameter of the tumors on CT was 10 mm (range, 6-15 mm). The tumors appeared as low-attenuation lesions with progressive enhancement during the arterial phase and early portal phase. Peak mean lesion attenuation was 60 +/- 27 H (enhancement, 23 H) at 64 sec. Peak mean lesion conspicuity was 80 +/- 18 H at 39 sec, occurring 10 sec before the peak mean hepatic attenuation of 135 +/- 15 H (enhancement, 67 H) at 49 sec. Relative lesion conspicuity paralleled relative enhancement of the liver throughout the imaging period.CONCLUSION:Although low-level tumor enhancement during the arterial phase and early portal phase reduced the conspicuity of small hypovascular tumors in this animal model, our results support the use of maximum liver enhancement as a marker for peak lesion conspicuity.

OBJECTIVEThe purpose of this study was to determine whether CT can be used to distinguish serous cystadenomas from mucinous cystadenomas or cystadenocarcinomas of the pancreas and play an enhanced role in patient triage and treatment.MATERIALS AND METHODSA blinded retrospective analysis of CT scans from 50 patients with pathologically proven primary cystic pancreatic neoplasms was performed independently by three radiologists. Using classic CT criteria as reported in the literature, each tumor was categorized as definitely serous, mucinous, or indeterminate. Tumor location, size, presence of calcification, and size of largest cyst were recorded. Data for each reviewer were analyzed independently. Consensus data were then subjected to multivariate logistic regression analysis.RESULTSThe ability of our reviewers to diagnose serous neoplasms ranged from 23% to 41%. Eight mucinous neoplasms were mistaken for serous tumors by two of the three reviewers. When consensus between at least two of the three reviewers was used for diagnosis, 27% of serous neoplasms were correctly diagnosed and all of the mucinous tumors were correctly identified as uncertain or mucinous, yielding the same clinical end point. For multivariate logistic regression analysis, a cyst smaller than 2 cm had a statistically significant association (p = 0.005) with serous tumors, and the presence of peripheral tumoral calcification had a statistically significant association (p = 0.01) with mucinous tumors.CONCLUSIONThere is significant variability in the CT appearance of serous and mucinous neoplasms of the pancreas, making CT an insensitive tool for differentiating these tumors. All tumors with peripheral calcifications were identified as mucinous neoplasms.

Study Design. This study examines pedicle widths, laminar thicknesses, and scalloping values for lumbosacral spine elements in Marfan volunteers. Comparisons were made between these measurements and norms as well as measurements between Marfan patients with and without dural ectasia.Objectives. To determine if the lumbosacral vertebral elements are altered in the patient with Marfan syndrome,Summary of Background Data. Several abnormalities have been noted in Marfan lumbar spine, including pedicular attenuation and widened interpediculate distances. This may be due to abnormalities of growth or presence of dural ectasia. Given the large numbers of Marfan patients requiring spinal surgery and the high postoperative failure rate, better understanding of the bony anatomy of Marfan lumbar spine is necessary, especially if use of instrumentation is anticipated.Methods, Thirty-two volunteers with Marfan syndrome based on the Ghent criteria underwent spiral computed tomography of the lumbosacral spine, images were evaluated for dural ectasia, and measurements of pedicle width, laminar thickness, and vertebral scalloping were made.Results. Pedicle widths and laminar thicknesses were significantly smaller in Marfan patients at all levels (P < 0.001), Mean pedicle widths at L1-L3 were smaller than the smallest available pedicle screw (5 mm). In Marfan patients with dural ectasia, laminar thickness from L5-S2 and pedicle widths at all lumbar levels were significantly reduced (P < 0.01). Vertebral scalloping at S1 was significantly greater in Marfan patients with dural ectasia (P = 0.02).Conclusion. Lumbar pedicle width and laminar thick:ness are significantly reduced in Marfan individuals, Those with dural ectasia demonstrate increased bony erosion of anterior and posterior elements of lumbosacral spine. Preoperative planning and routine computed tomography scans are recommended when operating on Marfan lumbosacral spine.

Purpose: To create criteria for detecting dural ectasia on MR or CT images in adult Marfan patients. Methods: Images were analyzed using a workstation. Parameters that predicted dural ectasia were included in our criteria. Results: Major criteria include: (1) width of dural sac below L5 > width above L4; (2) anterior sacral meningocele. Minor criteria include: (1) L5 nerve root sleeve diameter > 6.5 mm and (2) S1 scalloping > 3.5. Dural ectasia exists if 1 major or 2 minor criteria are present. Conclusion: MR and CT diagnose dural ectasia with high specificity and sensitivity. Our criteria accurately diagnose dural ectasia in adult Marfan patients.

Cryptococcoma of the sacrum was the initial presentation of systemic cryptococcosis in a patient on chronic steroid therapy for autoimmune hepatitis. The bone lesion was the only overt manifestation of systemic cryptococcal disease, which preceded other clinical manifestations and led to the subsequent diagnosis of systemic infection.

The basic tasks of spiral CT acquisition, image processing, and image display are the foundations underlying CT angiography regardless of the anatomic region of interest. Volume rendering is a rapidly emerging image processing technique for creating three-dimensional (3D) images from CT datasets, which has important advantages over other 3D rendering techniques including maximum intensity projection and surface rendering. This articles reviews the techniques that are commonly used in CT angiography and key considerations for optimization.

Volume visualization is gaining widespread acceptance in medical applications. As its use increases, the issue of accuracy becomes critical. There have been very few studies examining the accuracy of volume rendering techniques. We studied the accuracy of hardware-assisted volume rendering for measurement of arterial stenosis in computed tomography (CT) data. The results of our study reveal that accurate measurements can be made from volume rendered CT data. However, error is present (absolute average error from 5.1% to 13.6%) and there is some variability, even for experts (standard deviation ranged from 4.8% to 15%). The evidence suggests that the choice of volume rendering (transfer function) parameters greatly affects the accuracy of the results. Accurate transfer function parameter selection is a fiddicult problem. Parameters that produce realistic images often provide inaccurate measurements. As the use of volume visualization grows and more inexperienced users begin using these tools for medical diagnosis and staging, new guidelines, aids, and techniques must be developed to ensure reliable, accurate visualization results.

CT angiography, which has important advantages over both MR and ultrasound, is rapidly becoming an important modality for noninvasive evaluation of the neurovasculature. This article discusses CT angiography techniques for imaging the neurovasculature, including spiral acquisition protocols and image processing techniques, with a focus on the use of volume rendering for three-dimensional visualization. The clinical results for CT angiography of the cervical carotid arteries, intracranial aneurysms, arteriovenous malformations, and emerging work in the evaluation of acute stroke are reviewed. Important areas of ongoing research also are described.

Direct coronal CT of the wrist: helical acquisition with simplified patient positioning.B S Kuszyk and E K FishmanAudio Available | Share

Surgical resection is the cornerstone of curative therapy for primary and metastatic liver tumors. For best results, the surgeon must know the location of all hepatic tumor nodules relative to the major vessels that define the liver's surgical anatomy. Computed tomography is very sensitive for detecting liver tumors, but its planar slices do not fully address the three-dimensional nature of this surgical problem. We have developed a technique using volume rendering of computed tomography data that provides a preoperative 3D map of the liver showing tumor location relative to key blood vessels. This technique also has important implications for emerging, minimally invasive therapies.

OBJECTIVE An understanding of the normal appearance of hepatic tumors treated with cryosurgery is essential for accurately distinguishing normal postoperative changes from potential complications such as hepatic abscess or infarct, which may necessitate further interventions. The purpose of this study was to characterize the normal spectrum of CT findings after cryoablation of hepatic tumors. SUBJECTS AND METHODS The CT scans of 14 patients who had undergone hepatic cryoablation 4-16 days (mean, 7 days) before scanning were reviewed by three radiologists. None of these patients had postprocedural complications that necessitated intervention (e.g. abscess, infarct, or hemorrhage). Indications for cryoablation included primary hepatic tumors in four patients and hepatic metastases in 10 patients. CT findings were correlated with surgical findings in a lesion-by-lesion manner to ensure that only cryolesions were included in the analysis. RESULTS Twenty-eight cryolesions from 3 to 11 cm maximum diameter (mean, 7 cm) were detected on CT scans. All cryolesions were primarily hypodense and extended to the liver capsule. Ten (36%) of 28 lesions contained air, and 26 (93%) of 28 lesions contained hemorrhage. Thirteen (54%) of 24 lesions evaluated with i.v. contrast material showed peripheral enhancement. Cryolesions were primarily wedge shaped (54%), round (29%), or teardrop shaped (21%). One iatrogenic portosystemic shunt was detected. Other associated findings included subcapsular hemorrhage (29%), perihepatic fluid collections (43%), right-sided pleural effusion (93%), left-sided pleural effusion (64%), atelectasis of one or both lungs (93%), and ascites (7%). CONCLUSION The postoperative CT appearance of the liver in patients who underwent hepatic cryoablation without complications mimics that seen in the liver of patients with hepatic abscesses or infarcts. The CT appearance of the liver in patients undergoing cryosurgery needs to be carefully analyzed to avoid confusing normal findings related to the procedure with those related to procedural complications, it may be impossible to differentiate hepatic complications from normal postoperative changes on the basis of CT findings in many of these patients.

Both surface rendering and volume rendering have been extensively applied to CT data for 3-D visualization of skeletal pathology. This review illustrates potential limitations of each technique by directly comparing 3-D images of bone pathology created using volume rendering and surface rendering. Surface renderings show gross 3-D relationships most effectively, but suffer from more stairstep artifacts and fail to effectively display lesions hidden behind overlying bone or located beneath the bone cortex. Volume-rendering algorithms effectively show subcortical lesions, minimally displaced fractures, and hidden areas of interest with few artifacts. Volume algorithms show 3-D relationships with varying degrees of success depending on the degree of surface shading and opacity. While surface rendering creates more three-dimensionally realistic images of the bone surface, it may be of limited clinical utility due to numerous artifacts and the inability to show subcortical pathology. Volume rendering is a flexible 3-D technique that effectively displays a variety of skeletal pathology with few artifacts.