Saurabh Jha

Genetic and Pharmacologic Hydrogen Sulfide Therapy Attenuates Ischemia-Induced Heart Failure in Mice

Background— Hydrogen sulfide (H2S) is an endogenous signaling molecule with potent cytoprotective effects. The present study evaluated the therapeutic potential of H2S in murine models of heart failure. Methods and Results— Heart failure was induced by subjecting mice either to permanent ligation of the left coronary artery for 4 weeks or to 60 minutes of left coronary artery occlusion followed by reperfusion for 4 weeks. Transgenic mice with cardiac-restricted overexpression of the H2S-generating enzyme cystathione &ggr;-lyase (&agr;MHC-CGL-Tg+) displayed a clear protection against left ventricular structural and functional impairment as assessed by echocardiography in response to ischemia-induced heart failure, as well as improved survival in response to permanent myocardial ischemia. Exogenous H2S therapy (Na2S; 100 &mgr;g/kg) administered at the time of reperfusion (intracardiac) and then daily (intravenous) for the first 7 days after myocardial ischemia also protected against the structural and functional deterioration of the left ventricle by attenuating oxidative stress and mitochondrial dysfunction. Additional experiments aimed at elucidating some of the protective mechanisms of H2S therapy found that 7 days of H2S therapy increased the phosphorylation of Akt and increased the nuclear localization of 2 transcription factors, nuclear respiratory factor 1 and nuclear factor-E2-related factor (Nrf2), that are involved in increasing the levels of endogenous antioxidants, attenuating apoptosis, and increasing mitochondrial biogenesis. Conclusions— The results of the present study suggest that either the administration of exogenous H2S or the modulation of endogenous H2S production may be of therapeutic benefit in the treatment of ischemia-induced heart failure.

Adapting to Artificial Intelligence: Radiologists and Pathologists as Information Specialists

Artificial intelligence—the mimicking of human cognition by computers—was once a fable in science fiction but is becoming reality in medicine. The combination of big data and artificial intelligence, referred to by some as the fourth industrial revolution,1 will change radiology and pathology along with other medical specialties. Although reports of radiologists and pathologists being replaced by computers seem exaggerated,2 these specialties must plan strategically for a future in which artificial intelligence is part of the health care workforce. Radiologists have always revered machines and technology. In 1960, Lusted predicted “an electronic scannercomputer to examine chest photofluorograms, to separate the clearly normal chest films from the abnormal chest films.”3 Lusted further suggested that “the abnormal chest films would be marked for later study by the radiologists.”3 Lusted’s intuitions were prescient: interpreting radiographs is pattern recognition; computers can recognize patterns and may be helpful because some roentgenographic analyses can be automated. Nearly 60 years after Lusted’s prediction, Enlitic, a technology company in Silicon Valley, inputted images of normal radiographs and radiographs with fractures into a computerized database.4 Using deep learning, a refined version of artificial neural networks, the

Diagnostic performance of cardiac stress perfusion MRI in the detection of coronary artery disease using fractional flow reserve as the reference standard: a meta-analysis.

OBJECTIVE. This is an analysis of pooled studies for the determination of the test characteristics of stress perfusion cardiac MRI in the diagnosis of flow-limiting obstructive coronary artery disease (CAD) using fractional flow reserve (FFR) at catheter coronary angiography as the reference standard. MATERIALS AND METHODS. Traditionally, planimetric measurement of coronary stenosis at catheter coronary angiography has been considered the reference standard and has been used to verify the diagnostic characteristics of gatekeeper tests. FFR is a physiologic measure of flow limitation and is considered a more authentic reference standard in the diagnosis of CAD. The emergence of a new reference standard questions the true diagnostic accuracy of gatekeeper tests. A systematic literature review was performed for qualifying studies. The DerSimonian-Laird random effects model and a random-effects symmetric summary receiver operating characteristic curve analysis were performed. RESULTS. Twelve studies (761 patients) met the inclusion criteria. Four hundred six stenotic coronary arteries had FFR less than 0.75. Perfusion stress MRI has a sensitivity of 89.1% (95% CI, 84-93%) and specificity of 84.9% (95% CI, 76.6-91.1%) on a patient basis and a sensitivity of 87.7% (95% CI, 84.4-90.6%) and specificity of 88.6% (95% CI, 86.7-90.4%) on a coronary territory basis. CONCLUSION. Stress perfusion MRI remains an accurate test for the detection of flow-limiting stenosis when adjudicated by a physiologic reference standard.

From Imaging Gatekeeper to Service Provider — A Transatlantic Journey

A radiologist who made the transition from Britains gatekeeping mindset to that of an American service provider believes that as the U.S. health care system changes, he and his colleagues will need to play a more central role in clinical decision making.

Imaging Evaluation for Suspected Pulmonary Embolism: What Do Emergency Physicians and Radiologists Say?

OBJECTIVE The utility of various imaging techniques and strategies for the diagnosis of pulmonary embolism has been studied in randomized control trials and extensively described in the literature. CT and ventilation-perfusion scintigraphy are the mainstays of diagnosis, and MRI is emerging. The purpose of this study was to assess the diagnostic approach to pulmonary embolism practiced by emergency physicians and advised by radiologists. MATERIALS AND METHODS Questionnaires were sent to emergency physicians and radiologists in Pennsylvania. The questions covered diagnostic strategies for the detection of pulmonary embolism in the usual situations and in clinical circumstances in which the primary imaging technique is considered less desirable. RESULTS Sixty-two radiologists and 52 emergency physicians completed the survey. Ninety percent of radiologists and 96% of emergency physicians answered that CT was their first-line choice for the diagnosis of pulmonary embolism. The use of ventilation-perfusion scintigraphy increased in the care of patients with renal failure and allergy to iodinated contrast material. MRI was chosen infrequently. CONCLUSION CT is the overwhelmingly preferred technique for the diagnosis of pulmonary embolism. The role of ventilation-perfusion scintigraphy increases when the use of iodinated contrast material is contraindicated. MRI does not seem to have an important role in practice.

Frequency of Use of Imaging Tests in the Diagnosis of Pulmonary Embolism: Effects of Physician Specialty, Patient Characteristics, and Region

OBJECTIVE The purpose of this study was to ascertain whether clinical practice in diagnosing pulmonary embolism is consistent with recommendations in the literature and to explore variations in practice across site of care (e.g., emergency department), physician and patient characteristics, and geographic location. MATERIALS AND METHODS Medicare 5% research identifiable files were analyzed. The cases of patients with emergency department visits or inpatient stays for a diagnosis of pulmonary embolism or for symptoms related to pulmonary embolism (shortness of breath, chest pain, and syncope) were identified. We determined the number of patients who underwent each type of relevant imaging test and evaluated variations in the first non-chest-radiographic test by site of care and treating physician specialty. Using logistic regression, we studied variations in the use of common imaging tests, exploring variations associated with patient characteristics, physician specialty, site of care, and geographic location. RESULTS For patients in whom pulmonary embolism might have been suspected, the most common tests were echocardiography (26% of the patients), CT or CT angiography of the chest (11%), cardiac perfusion study (6.9%), and duplex ultrasound (7.3%). For patients with an inpatient diagnosis of pulmonary embolism, the most common tests were chest CT or CT angiography (49%), duplex ultrasound (18%), echocardiography (10.9%), and ventilation-perfusion scintigraphy (10.9%). For patients for whom pulmonary embolism might have been suspected, many large variations were found in practice patterns among physician specialties and geographic locations. There were fewer variations among patients with the inpatient diagnosis of pulmonary embolism. CONCLUSION Physician practice in the diagnosis of pulmonary embolism is broadly consistent with recommendations. However, variations by physician specialty and geographic location may be evidence of inappropriate imaging.

Congenital absence of the pericardium and its mimics

Congenital absence of the pericardium is a rare entity, with less than 400 cases reported in the literature. Pericardial absence is typically left sided, which results in herniation of the great vessels or portions of the heart. Patients may be asymptomatic, typical for complete defects, or can present with various degrees of chest pain in the setting of partial absence and strangulation. The finding may be isolated or associated with complex heart disease. We present a number of cases of pericardial absence that show isolated right- and left-sided defects, as well as entities in the differential diagnosis. Early recognition may decrease morbidity and mortality, resulting from delay in proper treatment.

Detection of strictures on upper gastrointestinal tract radiographic examinations after laparoscopic Roux-en-Y gastric bypass surgery: importance of projection.

OBJECTIVE Our objective was to determine the optimal radiographic projections for the detection of strictures at the gastrojejunal anastomosis after gastric bypass surgery. CONCLUSION Steep oblique or lateral spot images routinely should be obtained during upper gastrointestinal radiographic studies after gastric bypass surgery to optimize detection of strictures at the gastrojejunal anastomosis.

Phase-contrast MRI and applications in congenital heart disease.

A review of phase-contrast magnetic resonance imaging techniques, with specific application to congenital heart disease, is presented. Theory, pitfalls, advantages, and specific examples of multiple, well-described congenital heart disease presentations are discussed.

Supply/Demand in Radiology: A Historical Perspective and Comparison to other Labor Markets.

RATIONALE AND OBJECTIVES There has been attention on the job market recently and on radiologys supply/demand calculus. Supply is influenced by the number of trained radiologists, while demand is driven by demographics and technological innovation. We analyze the supply of radiologists historically and compare to other labor markets-medical and non-medical, domestic and foreign. MATERIALS AND METHODS We review National Resident Matching Program data in radiology and several other specialties from 1991 to 2015. We also review surveys, physician recruitment data, and peer-reviewed commentaries on medical specialty job markets. Trends are compared across specialties. The regulation of American medical training is compared to that in the United Kingdom and to a nonmedical labor market, unionized theatrical stage employees. RESULTS Radiology residency positions have increased since 1998 despite a downturn in the job market. This expansion coincides with a decreasing percentage of positions filled by domestic graduates. A similar trend has been seen in pathology, a notoriously oversupplied specialty. Conversely, other specialties have maintained their proportion of domestic graduates by way of limited supply or implicit demand. CONCLUSIONS The radiology job market is currently oversupplied, primarily a result of increasing residency positions despite indicators of decreasing demand. The percentage of residency positions filled by domestic graduates has decreased during the same period, suggesting that medical student interest is responsive to the market. Other specialties, particularly pathology, demonstrate the dangers of chronic oversupply. We advocate a reduction of radiology residency positions such that supply closely approximates demand without exceeding it. Additional measures may be taken, if necessary, to restore market equilibrium in the event of a mild undersupply.