Characteristics of Radiologists' Clinical Practice Patterns by Career Stage.

PURPOSE: To assess characteristics of radiologists' clinical practice patterns by career stage. METHODS: Radiologists' 2016 billed services were extracted from the Medicare Physician and Other Supplier Public Use File. Billed clinical work was weighted using work relative value units. Medical school graduation years were obtained from Medicare Physician Compare. Practice patterns were summarized by decades after residency. RESULTS: Among 28,463 included radiologists, 32.7% were ≤10 years postresidency, 29.3% 11-20 years, 25.0% 21-30 years, 10.5% 31-40 years, 2.4% 41-50 years, 0.1% ≥51 years. Billed clinical work (normalized to a mean of 1.00 among all radiologists) ranged 0.92-1.07 from 1 to 40 years, decreasing to 0.64 for 41-50 years and 0.43 for ≥51 years. Computed tomography represented 34.7%-38.6% of billed clinical work from 1 to 30 years, decreasing slightly to 31.5% for 31-40 years. Magnetic resonance imaging represented 13.9%-14.3% from 1 to 30 years, decreasing slightly to 11.2% for 31-40 years. Ultrasonography represented 6.2%-11.6% across career stages. Nuclear medicine increased steadily from 1.7% for ≤10 years to 7.0% for 41-50 years. Mammography represented 9.9%-12.9% from 1 to 50 years. Radiography/fluoroscopy represented 15.1%-29.8% from 1 to 50 years, but 65.9% for ≥51 years. CONCLUSION: The national radiologist workforce declines abruptly by more than half approximately 30 years after residency. Radiologists still working at 31-40 years, however, contribute similar billed clinical work, both overall and across modalities, as earlier career radiologists. Strategies to retain later-career radiologists in the workforce could help the specialty meet growing clinical demands, mitigate burnout in earlier career colleagues, and expand robust patient access to both basic and advanced imaging services.

Musculoskeletal Injuries Affecting Radiologists According to the 2017 ACR Human Resources Commission Workforce Survey.

Practice leaders surveyed in the 2017 ACR Human Resources Commission workforce survey reported that 25% of the radiologists or radiation oncologists they supervised had neck pain, 32% had low back pain, and 16% were dealing with a repetitive stress injury. The prevalence rates of these musculoskeletal ailments among radiologists and radiation oncologists were consistent with those reported in the literature in other populations. However, these prevalence rates may be underestimated because practice leaders, not the radiologists themselves, were surveyed, and the leaders may not be aware of all injuries.

Potential Radiation-Related Effects on Radiologists.

OBJECTIVE: The risk of injury associated with long-term occupational exposure to ionizing radiation is low for radiologists. The purpose of this article is to systematically review and inform radiologists about radiation-related effects to which they are potentially susceptible. CONCLUSION: Formal education and training on radiation safety and management, careful attention to good radiation protection habits, and continued emphasis on radiation management and the as low as reasonably achievable principle are recommended for all radiologists.

Addition of the Fleischner Society Guidelines to Chest CT Examination Interpretive Reports Improves Adherence to Recommended Follow-up Care for Incidental Pulmonary Nodules.

RATIONALE AND OBJECTIVES: The study aimed to determine whether the addition of the Fleischner Society guidelines to chest computed tomography (CT) reports identifying incidental pulmonary nodules affects follow-up care. PATIENTS AND METHODS: Beginning in 2008, a template containing the Fleischner Society guidelines was added at the interpreting radiologist's discretion to chest CT reports describing incidental solid pulmonary nodules at our institution. The records of all medical centers in Olmsted county were used to capture the complete medical history of local patients >35 years old diagnosed with a pulmonary nodule from April 1, 2008 to October 1, 2011. Patients with a history of cancer or previously diagnosed nodule, or who died before follow-up, were excluded. Patients were categorized according to whether they did ("template group") or did not ("control group") have the template added. Nodule size and smoking history were used to determine recommended follow-up care. Differences in follow-up were compared between groups using Pearson's chi-square test. RESULTS: A total of 510 patients (276 in the template group, 234 in the control group) were included in the study. Only 198 patients (39%) received their recommended follow-up care. Template group patients were significantly more likely to receive recommended follow-up care compared to control group patients (45% vs 31%, P = .0014). Most patients whose management did not adhere to Fleischner Society guidelines did not receive a recommended follow-up chest CT (210 out of 312, 67%). CONCLUSIONS: The addition of the Fleischner Society guidelines to chest CT reports significantly increases the likelihood of receiving recommended follow-up care for patients with incidental pulmonary nodules. Additional education is needed to improve appropriate guideline utilization by radiologists and adherence by ordering providers.

Evaluation of Posttreatment Follow-Up of Patients With Prostate Cancer Relative to the American College of Radiology's Appropriateness Criteria.

OBJECTIVE: The American College of Radiology (ACR) Appropriateness Criteria panel has recommended that patients with prostate cancer who have received treatment undergo imaging only after suspected cancer recurrence. We examined whether local physicians followed this recommendation and what types of imaging examinations were ordered in a cohort of patients with local prostate cancer. MATERIALS AND METHODS: The Rochester Epidemiology Project, a research consortium that collects, links, and stores medical record information of Olmsted County, Minnesota, residents, was used to capture the complete medical history of treated patients with prostate cancer from 2000 through 2011. Clinical information and imaging examinations performed were retrieved by chart review. Suspected recurrence was defined as treatment-specific prostate-specific antigen level elevations, bone pain, or abnormal digital rectal examination findings. RESULTS: Of the 670 treated patients with prostate cancer who were included in the final analysis, 129 (19%) underwent posttreatment imaging. After excluding imaging related to retreatment or another cancer, 13 patients (i.e., 2% of the entire cohort and 10% of imaged patients) underwent imaging in the absence of suspected recurrence. A total of 90 patients (70% of imaged patients) underwent imaging after suspected recurrence. Of these 90 patients, 62 (69%) underwent a bone scan as their first imaging modality either alone or in combination with other imaging modalities. Of the providers who ordered a bone scan first, 27% were urologists, 23% were radiation oncologists, and 24% were primary care physicians. CONCLUSION: Most patients in this study did not undergo imaging in the absence of suspected recurrence. Various types of imaging examinations were ordered for patients with suspected recurrence.

Transcriptomic and Immunohistochemical Profiling of SLC6A14 in Pancreatic Ductal Adenocarcinoma.

We used a target-centric strategy to identify transporter proteins upregulated in pancreatic ductal adenocarcinoma (PDAC) as potential targets for a functional imaging probe to complement existing anatomical imaging approaches. We performed transcriptomic profiling (microarray and RNASeq) on histologically confirmed primary PDAC tumors and normal pancreas tissue from 33 patients, including five patients whose tumors were not visible on computed tomography. Target expression was confirmed with immunohistochemistry on tissue microarrays from 94 PDAC patients. The best imaging target identified was SLC6A14 (a neutral and basic amino acid transporter). SLC6A14 was overexpressed at the transcriptional level in all patients and expressed at the protein level in 95% of PDAC tumors. Very little is known about the role of SLC6A14 in PDAC and our results demonstrate that this target merits further investigation as a candidate transporter for functional imaging of PDAC.

Gas-containing gallstones as a cause of the "effervescent gallbladder" sign and pneumobilia.

The "effervescent gallbladder" sign, the sonographic finding of tiny echogenic foci rising from the dependent portion of the gallbladder, reminiscent of bubbles rising in a glass of champagne, has been reported previously as a finding of emphysematous cholecystitis. We report two additional cases of this unusual finding in an asymptomatic patient and in a patient with acute, gangrenous cholecystitis, confirmed in both cases by CT, to be secondary to the release of gas from gallstones. These two cases cast doubt on the sonographic sign as a pathognomonic finding of emphysematous cholecystitis.

Monitoring the initial delivery of an oncolytic measles virus encoding the human sodium iodide symporter to solid tumors using contrast-enhanced computed tomography.

BACKGROUND: We aimed to determine the feasibility of monitoring viral delivery and initial distribution to solid tumors using iodinated contrast agent and micro-computed tomography (CT). METHODS: Human BxPC-3 pancreatic tumor xenografts were established in nude mice. An oncolytic measles virus with an additional transcriptional unit encoding the sodium iodide symporter (NIS), as a reporter for viral infection, was mixed with a 1:10 dilution of Omnipaque 300 (GE Healthcare, Milwaukee, WI, USA) contrast agent and injected directly into tumors. Mice were imaged with micro-CT immediately before and after injection to determine the location of contrast agent/virus mixture. Mice were imaged again on day 3 after injection with micro-single-photon emission CT/CT to determine the location of NIS-mediated (99m) TcO(4) transport. RESULTS: A 1:10 dilution of Omnipaque had no effect on viral infectivity or cell viability in vitro and was more than adequate for CT imaging of the intratumoral injectate distribution. The volume of tumor coverage with initial CT contrast agent and the 3-day postinfection measurement of virally infected tumor volume were significantly correlated. Additionally, regions of the tumor that did not receive contrast agent from the initial injection were largely devoid of viral infection at early time points. CONCLUSIONS: Contrast-enhanced viral delivery enables a rapid and accurate prediction of the initial viral distribution within a solid tumor. This technique should enable real-time monitoring of viral propagation from initially infected tumor regions to adjacent tumor regions.

Sodium iodide symporter (NIS)-mediated radiovirotherapy for pancreatic cancer.

OBJECTIVE: We have previously shown the therapeutic efficacy of an engineered oncolytic measles virus expressing the sodium iodide symporter reporter gene (MV-NIS) in mice with human pancreatic cancer xenografts. The goal of this study was to determine the synergy between MV-NIS-induced oncolysis and NIS-mediated (131)I radiotherapy in this tumor model. MATERIALS AND METHODS: Subcutaneous human BxPC-3 pancreatic tumors were injected twice with MV-NIS. Viral infection, NIS expression, and intratumoral iodide uptake were quantitated with (123)I micro-SPECT/CT. Mice with MV-NIS-infected tumors were treated with 0, 37, or 74 MBq (131)I and monitored for tumor progression and survival. Additional studies were performed with stable NIS-expressing tumors (BxPC-3-NIS) treated with 0, 3.7, 18.5, 37, or 74 MBq of (131)I. RESULTS: Mice treated with intratumoral MV-NIS exhibited significant tumor growth delay (p < 0.01) and prolonged survival (p = 0.02) compared with untreated mice. Synergy between MV-NIS-induced oncolysis and NIS-mediated (131)I ablation was not seen; however, a significant correlation was observed between NIS-mediated intratumoral iodide localization (% ID/g) and peak tumor volume reduction (p = 0.04) with combination MV-NIS and (131)I therapy. Stably transduced NIS-expressing BxPC-3 tumors exhibited rapid regression with > or = 18.5 MBq (131)I. CONCLUSION: Delivery of (131)I radiotherapy to NIS-expressing tumors can be optimized using micro-SPECT/CT imaging guidance. Significant hurdles exist for NIS as a therapeutic gene for combined radiovirotherapy in this human pancreatic cancer model. The lack of synergy observed with MV-NIS and (131)I in this model was not due to a lack of radiosensitivity but rather to a nonuniform intratumoral distribution of MV-NIS infection.

Quantitative molecular imaging of viral therapy for pancreatic cancer using an engineered measles virus expressing the sodium-iodide symporter reporter gene.

OBJECTIVE: Our objectives were to, first, determine the oncolytic potential of an engineered measles virus expressing the sodium-iodide symporter gene (MV-NIS) for intratumoral (i.t.) therapy of pancreatic cancer and, second, evaluate NIS as a reporter gene for in vivo monitoring and quantitation of MV-NIS delivery, viral spread, and gene expression in this tumor model. MATERIALS AND METHODS: Cultured human pancreatic cancer cells were infected with MV-NIS. Light microscopy, cell viability, and iodide uptake assays were used to confirm viral infection and NIS gene expression and function in vitro. Human pancreatic tumor xenografts were established in mice and infected via i.t. MV-NIS injections. NIS-mediated i.t. iodide uptake was quantitated by (123)I micro-SPECT/CT. i.t. MV-NIS infection was confirmed by immunohistochemistry of excised pancreatic xenografts. The oncolytic efficacy of MV-NIS was determined by measurement of tumor growth and mouse survival. RESULTS: Infection of human pancreatic cancer cell lines with MV-NIS in vitro resulted in syncytia formation, marked iodide uptake, and ultimately cell death. Tumor xenografts infected with MV-NIS concentrated radioiodine, allowing serial quantitative imaging with (123)I micro-SPECT/CT. i.t. MV-NIS therapy of human pancreatic cancer xenografts resulted in a significant reduction in tumor volume and increased survival time of the treated mice compared with the control mice. CONCLUSION: MV-NIS efficiently infects human pancreatic tumor cells and results in sufficient radioiodine uptake to enable noninvasive serial imaging and quantitation of the intensity, distribution, and time course of NIS gene expression. MV-NIS also shows oncolytic activity in human pancreatic cancer xenografts: Tumor growth is reduced and survival is increased in mice treated with the virus.

Small animal absorbed radiation dose from serial micro-computed tomography imaging.

PURPOSE: To determine the radiation dose to mouse cancer xenografts from serial micro-computed tomography (CT) examinations. PROCEDURES: A nude mouse with a 15-mm subcutaneous pancreatic cancer xenograft in the rightflank was used. Radiation exposure to the subcutaneous tumor and the mouse pancreas (to simulate an orthotopic pancreatic tumor model) was measured using lithium fluoride thermoluminescent dosimeters. Ultrafast micro-CT was performed using 80 kVp, 0.26 mA, 0.156 mm slice thickness, 256 slices, 0.7 mm Al filtration, and 60-second image acquisition time (15 mA second). Micro-CT imaging acquisitions were repeated four times. RESULTS: We measured consistently low tumor doses (0.014 to 0.02 Gy; average=0.017 Gy) per scan. Orthotopic doses in the region of the pancreas were also consistently low (0.014 to 0.018 Gy; average=0.016 Gy) per scan. CONCLUSIONS: Radiation doses delivered during ultrafast micro-CT serial imaging in the mouse are low and are likely below the threshold to affect tumor growth.

In vivo quantitation of intratumoral radioisotope uptake using micro-single photon emission computed tomography/computed tomography.

PURPOSE: This study was undertaken to determine the ability of micro-single photon emission computed tomography (micro-SPECT)/computed tomography (CT) to accurately quantitate intratumoral radioisotope uptake in vivo and to compare these measurements with planar imaging and micro-SPECT imaging alone. PROCEDURES: Human pancreatic cancer xenografts were established in 10 mice. Intratumoral radioisotope uptake was achieved via intratumoral injection of an attenuated measles virus vector expressing the NIS gene (MV-NIS). On various days after MV-NIS injection, (123)I planar and micro-SPECT/CT imaging was performed. Tumor activity was determined by dose calibrator measurements and region-of-interest (ROI) image analysis. Agreement and reproducibility of tumor activity measurements were assessed by Bland-Altman plots and Lin's concordance correlation coefficient (CCC). RESULTS: Intratumoral radioisotope uptake was detected in all mice. Scatterplots demonstrate strong agreement (CCC = 0.93) between micro-SPECT/CT ROI image analysis and dose calibrator tumor activity measurements. The differences between dose calibrator activity measurements and those obtained with ROI image analysis of micro-SPECT alone and planar imaging are less accurate and more variable (CCC = 0.84 and 0.78, respectively). CONCLUSIONS: Micro-SPECT/CT can be used to accurately quantify intratumoral radioisotope uptake in vivo and is more reliable than planar or micro-SPECT imaging alone.

CT fluoroscopy-guided biopsy of the lung or upper abdomen with a breath-hold monitoring and feedback system: a prospective randomized controlled clinical trial.

PURPOSE: To prospectively determine the clinical effectiveness of a breath-hold monitoring and feedback system in computed tomographic (CT) fluoroscopy-guided biopsies in which respiratory motion is a problem. MATERIALS AND METHODS: Institutional review board approval and oral and written informed consent were obtained. This study was HIPAA compliant. A bellows-based system was used to monitor respiration and provide patient feedback. A randomized controlled clinical trial compared intermittent mode CT fluoroscopy-guided biopsies of the lung or upper abdomen performed with (n = 56) and without (n = 57) the bellows system. Inclusion criteria for 113 patients were lesions 6 cm or smaller in maximum dimension that were not affixed to the chest or abdominal wall. Primary outcome measurements were CT fluoroscopy exposure time and patient dose. Wilcoxon rank sum, chi(2), and Fisher exact tests were used for statistical analysis. RESULTS: Median CT fluoroscopy exposure time was 12.6 seconds (range, 2.4-44.4 seconds) for the bellows group and 18.0 seconds (range, 6.0-118.0 seconds) for the nonbellows group (P = .004). Patient dose was decreased in the bellows group (median dose, 29.5 mGy; range, 4.7-135.8 mGy) versus the nonbellows group (median, 41.3 mGy; range, 11.8-155.9 mGy) (P = .01). Lesions were accessed successfully with one needle puncture attempt in 43 of 56 patients (77%) in the bellows group and 30 of 57 patients (53%) in the nonbellows group (P = .007). Pneumothorax developed in 11 of 50 patients (22%) in the bellows group who underwent lung biopsy compared with 16 of 50 (32%) patients in the nonbellows group. CONCLUSION: A breath-hold monitoring and feedback system allows depiction of mobile target lesions throughout CT fluoroscopy-guided biopsy of the lung and upper abdomen.

Intermittent-mode CT fluoroscopy-guided biopsy of the lung or upper abdomen with breath-hold monitoring and feedback: system development and feasibility.

A bellows-based breath-hold monitoring and feedback system was developed and evaluated for use in intermittent-mode computed tomographic (CT) fluoroscopy-guided biopsy procedures in the lung or upper abdomen. The bellows system is described, and its feasibility is demonstrated in studies with a respiratory phantom and human volunteers. Results are reported for seven patients who underwent bellows-assisted biopsy. Breath-hold monitoring and feedback with the bellows system allow the patient to perform reliable breath holding at a preselected level. This optimizes intermittent-mode CT fluoroscopy-guided biopsies by allowing consistent visualization of the target lesion throughout the procedure.