Arun C. Nachiappan

Postoperative Imaging in Liver Transplantation: What Radiologists Should Know

Liver transplantation is now frequently used in the treatment of end-stage liver disease. Therefore, it is important that radiologists be aware of common anastomotic techniques and expected postoperative imaging findings. Imaging is most useful in evaluating for posttransplantation complications, which are broadly classified into vascular, biliary, and other complications. Hepatic artery thrombosis is the most significant complication and is often associated with graft failure. Radiologists have multiple modalities at their disposal for optimal evaluation. Doppler ultrasonography (US) is the preliminary imaging modality for gross evaluation of the liver parenchyma, biliary tree, and vasculature for abnormalities. When US findings are indeterminate or there is persistent clinical suspicion for an abnormality, computed tomography (CT) is often performed. The major indications for CT are detection of bile leak, hemorrhage, and abscess, but CT is also useful in the assessment of the vasculature. T-tube cholangiography and magnetic resonance cholangiopancreatography are the best noninvasive imaging tools for evaluating for biliary stricture. Some investigators would argue that endoscopic retrograde cholangiopancreatography (ERCP) is a better diagnostic imaging modality; however, ERCP is invasive. Hepatobiliary scintigraphy is optimal for the evaluation of biliary leakage. Early detection of posttransplantation complications will help lower morbidity rates and will likely allow graft salvage in selected cases.

The Thyroid: Review of Imaging Features and Biopsy Techniques with Radiologic-Pathologic Correlation

Knowledge of the normal and abnormal imaging appearances of the thyroid gland is essential for appropriate identification and diagnosis of thyroid lesions. Thyroid nodules are often detected incidentally at computed tomography, magnetic resonance imaging, and positron emission tomography; however, ultrasonography (US) is the most commonly used imaging modality for characterization of these nodules. US characteristics that increase the likelihood of malignancy in a thyroid nodule include microcalcifications, solid composition, and central vascularity. Nuclear scintigraphy is commonly used for evaluation of physiologic thyroid function and for identification of metabolically active and inactive nodules. When fine-needle aspiration biopsy (FNAB) of a lesion is indicated based on clinical and radiologic features, appropriate US-guided biopsy technique and careful cytologic analysis are crucial for making the diagnosis. FNAB and core biopsy are the two percutaneous techniques used to obtain a specimen, with the latter technique being indicated following nondiagnostic or indeterminate FNAB. Specimen adequacy and diagnostic accuracy vary due to several factors, including location of aspiration and biopsy technique used. The radiologist must have a basic knowledge of thyroid disease, be familiar with specimen processing, and recognize the cytologic and radiologic appearances of thyroid lesions, all of which will facilitate the management of these lesions. Online supplemental material is available for this article.

Laparoscopic sleeve gastrectomy: a guide to postoperative anatomy and complications

Abstract:The purpose of this pictorial essay is to review the surgical technique, postoperative anatomy, and potential complications of the laparoscopic sleeve gastrectomy. As the laparoscopic sleeve gastrectomy becomes an increasingly popular bariatric surgery, it is important for radiologists to familiarize themselves with the procedure and possible complications.

Pulmonary Tuberculosis: Role of Radiology in Diagnosis and Management.

Tuberculosis is a public health problem worldwide, including in the United States-particularly among immunocompromised patients and other high-risk groups. Tuberculosis manifests in active and latent forms. Active disease can occur as primary tuberculosis, developing shortly after infection, or postprimary tuberculosis, developing after a long period of latent infection. Primary tuberculosis occurs most commonly in children and immunocompromised patients, who present with lymphadenopathy, pulmonary consolidation, and pleural effusion. Postprimary tuberculosis may manifest with cavities, consolidations, and centrilobular nodules. Miliary tuberculosis refers to hematogenously disseminated disease that is more commonly seen in immunocompromised patients, who present with miliary lung nodules and multiorgan involvement. The principal means of testing for active tuberculosis is sputum analysis, including smear, culture, and nucleic acid amplification testing. Imaging findings, particularly the presence of cavitation, can affect treatment decisions, such as the duration of therapy. Latent tuberculosis is an asymptomatic infection that can lead to postprimary tuberculosis in the future. Patients who are suspected of having latent tuberculosis may undergo targeted testing with a tuberculin skin test or interferon-γ release assay. Chest radiographs are used to stratify for risk and to assess for asymptomatic active disease. Sequelae of previous tuberculosis that is now inactive manifest characteristically as fibronodular opacities in the apical and upper lung zones. Stability of radiographic findings for 6 months distinguishes inactive from active disease. Nontuberculous mycobacterial disease can sometimes mimic the findings of active tuberculosis, and laboratory confirmation is required to make the distinction. Familiarity with the imaging, clinical, and laboratory features of tuberculosis is important for diagnosis and management. ©RSNA, 2017.

Large Multilocular Thymic Cyst: A Rare Finding in an HIV Positive Adult Female

Multilocular thymic cysts with follicular hyperplasia are uncommon masses that occur in Human Immunodeficiency Virus (HIV) positive individuals. These cysts mostly present in HIV positive children. Here we report a rare case of multilocular thymic cyst in an HIV positive adult female. In this case report, the radiologic findings of multilocular thymic cyst, management and prognosis are discussed.

Clinically Oriented Three-Year Medical Physics Curriculum: A New Design for the Future

OBJECTIVE Medical physics instruction for diagnostic radiology residency at our institution has been redesigned with an interactive and image-based approach that encourages clinical application. The new medical physics curriculum spans the first 3 years of radiology residency and is integrated with the core didactic curriculum. CONCLUSION Salient features include clinical medical physics conferences, fundamentals of medical physics lectures, practicums, online modules, journal club, and a final review before the American Board of Radiology core examination.

Case 195: chondrosarcoma of the posterior mediastinum.

Although chondrosarcoma is rare in the spine, it should be considered when there is a ring and arc appearance of calcifications within adjacent bone and heterogeneous high T2 signal intensity within a paraspinal mass.

Radiologic Pseudoprogression during Anti–PD-1 Therapy for Advanced Non–Small Cell Lung Cancer

Introduction: Anti–programmed cell death protein 1 (PD‐1) therapy can lead to unconventional tumor responses, including radiologic pseudoprogression. Here we have determined the real‐world incidence of radiologic pseudoprogression in advanced NSCLC and compared radiologic response criteria for assessment of disease response. Methods: The electronic medical records of all patients with NSCLC who were receiving anti–PD‐1 therapy at our institution over a 3‐year period were retrospectively reviewed, and patients with clinically suspected radiologic pseudoprogression were identified. Patients without available follow‐up imaging or clinical data were excluded. Imaging examinations were then analyzed to determine whether progression was confirmed on subsequent reimaging. Assessments of tumor response by the Response Evaluation Criteria in Solid Tumors (RECIST), version 1.1 (RECIST 1.1), the unidimensional immune‐related response criteria (iRRC), and the iRECIST criteria for all patients were performed and compared. Results: A total of 228 consecutive patients began receiving anti–PD‐1 therapy over a 3‐year period. Of the 166 of these patients who were evaluable, most (80%) received nivolumab. Fifteen patients (9%) were clinically suspected of having radiologic pseudoprogression on account of tumor enlargement and/or development of new lesions on computed tomography images during the first 4 to 6 weeks of therapy, and they continued receiving anti–PD‐1 therapy. Three of these patients (2%) demonstrated evidence of radiologic pseudoprogression at first reimaging. The iRRC and immune RECIST criteria were more accurate in classifying radiologic pseudoprogression as nonprogression; none of the three cases were deemed progression by the iRRC or immune RECIST, whereas all three cases were determined to be progression according to the Response Evaluation Criteria in Solid Tumors, version 1.1. Conclusions: Radiologic pseudoprogression is a clinical challenge but an uncommon occurrence in patients with NSCLC who are receiving anti–PD‐1 therapy.

Limited Utility of Pulmonary Nodule Risk Calculators for Managing Large Nodules

RATIONALE AND OBJECTIVES The optimal management of large pulmonary nodules, at higher risk for lung cancer, has not been determined, and it remains unclear as to which patients should undergo follow-up imaging vs invasive tissue diagnosis via biopsy or surgical resection. MATERIALS AND METHODS Through search of radiology reports, 86 nodules from our institution were identified using the inclusion criterion of solid nodules measuring greater than 8mm. We evaluated these nodules with a number of risk prediction calculators, including the Brock University model, and compared these against the proven diagnosis. RESULTS Of 86 nodules, 59 (69%) nodules were malignant. The most accurate predictive model, the Brock University calculator, underestimated the risk for this group at 33%. At its optimal threshold, this model had a positive predictive value of 81% and negative predictive value of 53%. Notwithstanding the low negative predictive value, the positive predictive value was no better than patients clinically selected for biopsy (86% of biopsies were malignant). CONCLUSION Existing nodule risk prediction calculators are of limited usage in guiding the management of large pulmonary nodules. At present, the accuracy of these models in this setting is inferior to expert clinical judgment, and future work is needed to develop management algorithms for higher-risk nodules.

The value of delayed phase enhanced imaging in malignant pleural mesothelioma

BACKGROUND Cross-sectional imaging of malignant pleural mesothelioma (MPM) can underestimate the presence of local tumor invasion. Since accurate staging is vital optimal choice of therapy, techniques that optimize pleural imaging are needed. Here we estimate the optimal timing of MPM enhancement on magnetic resonance imaging (MRI). METHODS All MPM patients with intravenous (IV) contrast enhanced staging MRI between 2000-2016 at our institution were retrospectively selected for image analysis. Patients with incomplete imaging protocol and maximum pleural tumor thickness <1 cm were excluded. Quantitative measurements of tumor signal intensity were obtained on pre-contrast and post-contrast phases where MRI acquisition parameters were fixed. Using best-fit model curves, predicted maximum time points of enhancement were determined using a simulation of predicted values. Additionally, a qualitative assessment of tumor conspicuity was performed at all IV contrast time delays imaged. A statistical analysis assessed for correlation between qualitative lesion conspicuity and quantitative tumor enhancement. RESULTS Of the 42 MPM patients who had undergone staging MRI during the study period, 12 patients met the study criteria. Peak tumor enhancement was between 150 and 300 sec following IV contrast administration. Within this time window, 80% of patients are projected to have reached >80%, >85%, and >90% peak tumor enhancement. There was a statistically significant correlation between increasing tumor enhancement and subjective lesion conspicuity. CONCLUSIONS Optimal MPM enhancement on MRI likely occurs at a time delay between 2.5-5 min following IV contrast administration. Further study of delayed phase enhancement of MPM with dynamic contrast enhanced MRI is warranted.