Faculty Bibliography

The axilla contains several important structures which exist in a relatively confined anatomic space between the neck, chest wall, and upper extremity. While neoplastic lymphadenopathy may be among the most common axillary conditions, many other processes may be encountered. For example, expanded use of axillary vessels for access routes for endovascular procedures will increase the need for radiologists to access vessel anatomy, patency, and complications that may arise. Knowledge of axillary anatomy and pathology will allow the imager to systematically evaluate the axillae using various imaging modalities.

The first year of radiology residency presents many unique challenges, from transitioning into a completely new, specialized field to preparing for call. Implementation of a longitudinal lecture series dedicated towards the clinical demands of being a first-year radiology resident may improve their knowledge and comfort level, as well as benefit the entire program. In this article, we outline our experience with the development of a resident-led dedicated first-year radiology resident lecture series providing targeted, high-yield instruction on rotation logistics, basic physics and artifacts, examination protocolling, and common and "don't miss" pathology.

Background Isoattenuating and hyperattenuating thymic cysts at CT are often misinterpreted as lymphadenopathy or thymic epithelial neoplasms. Purpose To evaluate the longitudinal change in thymic cyst appearance at CT and MRI. Materials and Methods All chest MRI studies showing thymic cysts between July 2008 and December 2019, identified from a retrospective search of a quality assurance database, were included in this study if initial CT depicted a thymic lesion, the patient was referred for follow-up MRI for characterization, and the baseline (ie, index) MRI indicated a cystic lesion. Follow-up CT scans and/or MRI scans were identified through July 2020. Thymic cyst characteristics, such as size, location, and morphologic features, as well as CT and MRI characteristics, were recorded. Change in size, attenuation, and T1-weighted MRI signal was assessed longitudinally. Descriptive statistics of longitudinal change were tabulated. Results A total of 244 chest MRI studies in 140 patients with 142 unique cysts and 392 CT examinations (636 total examinations and 645 thymic cysts-nine examinations with two cysts each) were evaluated. The median follow-up duration was 2.2 years. Thirty-three patients with 34 unique cysts (34 of 142 cysts [24%]) underwent imaging follow-up for more than 5 years. Thymic cysts followed up for more than 5 years were most commonly saccular (189 of 274 cysts [69% axially]) and retrosternal (14 of 34 cysts [41%]). Craniocaudal dimension was larger than transverse and anteroposterior dimensions in 223 of 274 cysts (81%). Mean thymic cyst attenuation was 25 HU (range, 15-100 HU). Five of 31 cysts (16%) exhibited wall calcification. The median cyst wall thickness was 2.0 mm (range, 0.9-3.0 mm). Most thymic cysts changed in volume (31 of 34 cysts [91%]), CT attenuation (15 of 35 cysts [43%]), and T1-weighted MRI signal (12 of 18 cysts [67%]) over time. None developed mural irregularity, nodularity, or septations. Conclusion Unilocular thymic cysts, defined at index MRI, never developed irregular wall thickening, mural nodularity, or septations that would raise concern for malignant transformation. However, these cysts showed mural calcification and change in size, CT attenuation, and MRI signal over more than 5 years of follow-up. © RSNA, 2021 Online supplemental material is available for this article.

KRAS G12C mutations are important oncogenic mutations that confer sensitivity to direct G12C inhibitors. We retrospectively identified patients with KRAS+ NSCLC from 2015 to 2019 and assessed the imaging features of the primary tumor and the distribution of metastases of G12C NSCLC compared to those of non-G12C KRAS NSCLC and NSCLC driven by oncogenic fusion events (RET, ALK, ROS1) and EGFR mutations at the time of initial diagnosis. Two hundred fifteen patients with KRAS+ NSCLC (G12C: 83; non-G12C: 132) were included. On single variate analysis, the G12C group was more likely than the non-G12C KRAS group to have cavitation (13% vs. 5%, p = 0.04) and lung metastasis (38% vs. 21%; p = 0.043). Compared to the fusion rearrangement group, the G12C group had a lower frequency of pleural metastasis (21% vs. 41%, p = 0.01) and lymphangitic carcinomatosis (4% vs. 39%, p = 0.0001) and a higher frequency of brain metastasis (42% vs. 22%, p = 0.005). Compared to the EGFR+ group, the G12C group had a lower frequency of lung metastasis (38% vs. 67%, p = 0.0008) and a higher frequency of distant nodal metastasis (10% vs. 2%, p = 0.02). KRAS G12C NSCLC may have distinct primary tumor imaging features and patterns of metastasis when compared to those of NSCLC driven by other genetic alterations.

Reports are rising of patients with unilateral axillary lymphadenopathy, visible on diverse imaging examinations, after recent coronavirus disease 2019 vaccination. With less than 10% of the US population fully vaccinated, we can prepare now for informed care of patients imaged after recent vaccination. The authors recommend documenting vaccination information (date[s] of vaccination[s], injection site [left or right, arm or thigh], type of vaccine) on intake forms and having this information available to the radiologist at the time of examination interpretation. These recommendations are based on three key factors: the timing and location of the vaccine injection, clinical context, and imaging findings. The authors report isolated unilateral axillary lymphadenopathy (i.e., no imaging findings outside of visible lymphadenopathy), which is ipsilateral to recent (prior 6 weeks) vaccination, as benign with no further imaging indicated. Clinical management is recommended, with ultrasound if clinical concern persists 6 weeks after the final vaccination dose. In the clinical setting to stage a recent cancer diagnosis or assess response to therapy, the authors encourage prompt recommended imaging and vaccination (possibly in the thigh or contralateral arm according to the location of the known cancer). Management in this clinical context of a current cancer diagnosis is tailored to the specific case, ideally with consultation between the oncology treatment team and the radiologist. The aim of these recommendations is to (1) reduce patient anxiety, provider burden, and costs of unnecessary evaluation of enlarged nodes in the setting of recent vaccination and (2) avoid further delays in vaccinations and recommended imaging for best patient care during the pandemic.

BACKGROUND AND PURPOSE:Severe respiratory distress in patients with COVID-19 has been associated with higher rate of neurologic manifestations. Our aim was to investigate whether the severity of chest imaging findings among patients with coronavirus disease 2019 (COVID-19) correlates with the risk of acute neuroimaging findings. MATERIALS AND METHODS:This retrospective study included all patients with COVID-19 who received care at our hospital between March 3, 2020, and May 6, 2020, and underwent chest imaging within 10 days of neuroimaging. Chest radiographs were assessed using a previously validated automated neural network algorithm for COVID-19 (Pulmonary X-ray Severity score). Chest CTs were graded using a Chest CT Severity scoring system based on involvement of each lobe. Associations between chest imaging severity scores and acute neuroimaging findings were assessed using multivariable logistic regression. RESULTS:= .041). The pulmonary x-ray severity score was a significant predictor of acute neuroimaging findings in patients with COVID-19. CONCLUSIONS:Patients with COVID-19 and acute neuroimaging findings had more severe findings on chest imaging on both radiographs and CT compared with patients with COVID-19 without acute neuroimaging findings. The severity of findings on chest radiography was a strong predictor of acute neuroimaging findings in patients with COVID-19.