Mechanistic Insights Gained by High Spatial Resolution Reactivity Mapping of Homogeneous and Heterogeneous (Electro)Catalysts.

The recent development of high spatial resolution microscopy and spectroscopy tools enabled reactivity analysis of homogeneous and heterogeneous (electro)catalysts at previously unattainable resolution and sensitivity. These techniques revealed that catalytic entities are more heterogeneous than expected and local variations in reaction mechanism due to divergences in the nature of active sites, such as their atomic properties, distribution, and accessibility, occur both in homogeneous and heterogeneous (electro)catalysts. In this review, we highlight recent insights in catalysis research that were attained by conducting high spatial resolution studies. The discussed case studies range from reactivity detection of single particles or single molecular catalysts, inter- and intraparticle communication analysis, and probing the influence of catalysts distribution and accessibility on the resulting reactivity. It is demonstrated that multiparticle and multisite reactivity analyses provide unique knowledge about reaction mechanism that could not have been attained by conducting ensemble-based, averaging, spectroscopy measurements. It is highlighted that the integration of spectroscopy and microscopy measurements under realistic reaction conditions will be essential to bridge the gap between model-system studies and real-world high spatial resolution reactivity analysis.

Multicenter survey clarifying phrases in emergency radiology reports.

PURPOSE: Interactions between radiologists and emergency physicians are often diminished as imaging volume increases and more radiologists read off site. We explore how several commonly used phrasings are perceived by radiologists and emergency physicians to decrease ambiguity in reporting. METHODS: An anonymous survey was distributed to attendings and residents at seven academic radiology and emergency departments across the USA via a digital platform as well as to an email group consisting of radiologists across the country with an interest in quality assurance. Physicians were asked to assign a percent score to probabilistic phrases such as, "suspicious of," or "concerned for." Additional questions including, "how often the report findings are reviewed," "what makes a good radiology report," and "when is it useful to use the phrase 'clinical correlation are recommended.'" Median scores and confidence intervals were compared using an independent Student's T-test. RESULTS: Generally, there was agreement between radiologists and emergency room physicians in how they interpret probabilistic phrases except for the phrases, "compatible with," and "subcentimeter liver lesions too small to characterize." Radiologists consider a useful report to answer the clinical question, be concise, and well organized. Emergency physicians consider a useful report to be concise, definitive or include a differential diagnosis, answer the clinical question, and recommend a next step. Radiologists and emergency physicians did not agree on the usefulness of the phrase, "clinical correlation recommended," in which radiologists found the phrase more helpful under particular circumstances. CONCLUSION: The survey demonstrated a wide range of answers for probabilistic phrases for both radiologists and emergency physicians. While the medians and means of the two groups were often different by statistical significance, the actual percent difference was minor. These wide range of answers suggest that use of probabilistic phrases may sometimes lead to misinterpretation between radiologist and emergency room physician and should be avoided or defined if possible.

Recurrent Adult Sacrococcygeal Teratoma Developing Adenocarcinoma: A Case Report and Review of Literatures.

Sacrococcygeal teratomas (SCT) are most commonly seen in infants and children but are rare in adults. Most adult SCT are benign and mature with a minority of tumors having immature components or overt malignancy. Here, we report a 65-year-old female with a SCT developing adenocarcinoma. The patient was diagnosed with benign sacrococcygeal cystic teratoma on her initial hospital visit and was treated with surgical resection. She was followed up postoperatively and was noted to have a markedly elevated CA 19-9 level 13 months after the surgery. Radiological and clinical examination revealed thickening of the perirectal soft tissues, located near the inferior portion of her previous incision site. Histological evaluation of the lesion showed invasive, moderately differentiated adenocarcinoma. Immunohistochemical staining results were suggestive, but not diagnostic, of anal gland adenocarcinoma. This case report expands the knowledge regarding an adenocarcinoma arising from a previously benign, adult SCT.

Semi-Automated 3D Volumetric Renal Measurements in Polycystic Kidney Disease Using b0-Images-A Feasibility Study.

Autosomal dominant polycystic kidney disease (ADPKD) eventually leads to end stage renal disease (ESRD) with an increase in size and number of cysts over time. Progression to ESRD has previously been shown to correlate with total kidney volume (TKV). An accurate and relatively simple method to perform measurement of TKV has been difficult to develop. We propose a semi-automated approach of calculating TKV inclusive of all cysts in ADPKD patients based on b0 images relatively quickly without requiring any calculations or additional MRI time. Our purpose is to evaluate the reliability and reproducibility of our method by raters of various training levels within the environment of an advanced 3D viewer. Thirty patients were retrospectively identified who had DWI performed as part of 1.5T MRI renal examination. Right and left TKVs were calculated by five radiologists of various training levels. Interrater reliability (IRR) was estimated by computing the intraclass correlation (ICC) for all raters. ICC values calculated for TKV measurements between the five raters were 0.989 (95% CI = (0.981, 0.994), p < 0.01) for the right and 0.961 (95% CI = (0.936, 0.979), p < 0.01) for the left. Our method shows excellent intraclass correlation between raters, allowing for excellent interrater reliability.

Peripheral arterial occlusion due to COVID-19: CT angiography findings of nine patients.

BACKGROUND: Reports have indicated an association of large vessel peripheral arterial occlusion in the setting of Coronavirus Disease 2019 (COVID-19). While prior investigations have mostly focused on venous or cerebral arterial occlusions, we examined patients presenting exclusively with peripheral arterial extremity occlusions to investigate for any predisposing factors in this subset of COVID-19 patients. MATERIALS AND METHODS: This is a retrospective study of COVID-19 patients with peripheral arterial occlusions presenting to a multi-hospital health care system in New York City between February 1st, 2020 and April 30th, 2020. Patient data and computed tomography angiography (CTA) exams in this subset were then collected and analyzed. RESULTS: For the months of February, March, and April 2020, we identified 9 patients (ages 37-93 yrs) at our health care system who underwent extremity CTA for large vessel upper or lower extremity arterial occlusion and were diagnosed with COVID-19. Patient medical histories and clinical parameters were evaluated to identify common risk factors including obesity, hypertension, hyperlipidemia, and diabetes. Patients presented with increased inflammatory markers including ferritin, erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) as well as increased D-dimer. CONCLUSION: Our findings suggest patients with COVID-19 and comorbidities presenting with elevated inflammatory markers and D-dimer may be at increased risk of large vessel peripheral arterial occlusion.

Conservative management of uterine rupture in gestational trophoblastic neoplasia.

•Uterine artery embolization as management of uterine rupture due to invasive GTN.•Fertility preservation for select cases of uterine rupture due to invasive GTN.•Conservative surgery and chemotherapy for invasive GTN with uterine rupture.

The utility of abdominopelvic CT in pregnant patients with abdominal pain and a negative or inconclusive abdominal MRI.

Pregnant women with abdominal pain can pose a diagnostic dilemma due to the nonspecific nature of symptoms and the desire to avoid radiation to the conceptus. Many algorithms will suggest ultrasound (US) or Magnetic Resonance Imaging (MRI) as the first-line imaging choice in pregnant women with abdominal pain due to the lack of ionizing radiation. However, these studies can have limitations as well. Abdominopelvic MRI is susceptible to respiratory motion that could cause a study to be nondiagnostic (Zaitsev et al., 2015 [1]). In the current case series, we present 8 pregnant patients with abdominal pain who underwent CT abdomen and pelvis after negative or inconclusive abdominal MRI exams. To our knowledge, this is the only case series that describes CT findings in the pregnant population after negative or inconclusive MRI.

Multimodality Imaging of the Pancreatic Neuroendocrine Tumors.

Pancreatic neuroendocrine tumors (PNETs) are uncommon pancreatic masses which arise from amine precursor and uptake decarboxylation cells. They are classified as functional or nonfunctional based on the associated clinical symptoms. Insulinomas and gastrinomas are the most common functional tumors. PNETs are also classified based on their biologic behavior as benign or malignant. While most PNETs are sporadic, a small percentage are associated with syndromes such as multiple endocrine neoplasia type 1, von Hippel-Lindau syndrome, and are usually multiple in those cases. On imaging, most PNETs are circumscribed and hypervascular masses; however, larger tumors are often heterogeneous. The presence of calcification, cystic degeneration, and necrosis increases the likelihood of malignancy and carries a poor prognosis. Metastases have similar imaging appearance to the primary lesion and are most commonly seen in the liver, locoregional lymph nodes, and bone. This article reviews the pathologic and radiologic features of pancreatic neuroendocrine tumors as well as imaging mimics and their distinguishing features.

Nontraumatic large bowel perforation: spectrum of etiologies and CT findings.

Large bowel perforation is an abdominal emergency that results from a wide range of etiologies. Computed tomography is the most reliable modality in detecting the site of large bowel perforation. The diagnosis is made by identifying direct CT findings such as extraluminal gas or contrast and discontinuity along the bowel wall. Indirect CT findings can help support the diagnosis, and include bowel wall thickening, pericolic fat stranding, abnormal bowel wall enhancement, abscess, and a feculent collection adjacent to the bowel. Common etiologies that cause large bowel perforation are colon cancer, foreign body aspiration, stercoral colitis, diverticulitis, ischemia, inflammatory and infectious colitides, and various iatrogenic causes. Recognizing a large bowel perforation on CT can be difficult at times, and there are various entities that may be misinterpreted as a colonic perforation. The purpose of this article is to outline the MDCT technique used for evaluation of suspected colorectal perforation, discuss relevant imaging findings, review common etiologies, and point out potential pitfalls in making the diagnosis of large bowel perforation.

ACR Appropriateness Criteria® Hematospermia.

Most men with hematospermia or hemospermia (HS) are young (<40 years of age), presenting with transient or episodic HS without other signs or symptoms of disease. The condition is self-limiting in most cases and idiopathic in nature. When a cause can be identified, infections of the urogenital tract are the most common. Imaging does not play a role in this patient population. In older men (>40 years of age), clinical screening for prostate cancer is advised. Furthermore, when HS is persistent or has symptoms, causes include obstruction or stricture at the level of the verumontanum, calcifications or calculi in the prostate, ejaculatory ducts or seminal vesicles, and cysts arising within these structures. Noninvasive imaging, predominantly transrectal ultrasound (TRUS) and MRI, can be used in men of any age with persistent or refractory HS, or other associated symptoms or signs. TRUS is considered as the first-line imaging with MRI used when TRUS is inconclusive or negative. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision include an extensive analysis of current medical literature from peer-reviewed journals and the application of well-established methodologies (RAND/UCLA Appropriateness Method and Grading of Recommendations Assessment, Development, and Evaluation or GRADE) to rate the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where evidence is lacking or equivocal, expert opinion may supplement the available evidence to recommend imaging or treatment.

Clues to vascular disorders at non-contrast CT of the chest, abdomen, and pelvis.

Non-contrast chest CT scans are commonly performed while CT scans of the abdomen and pelvis are performed in a select subset of patients; those with limited renal function, an allergy to iodinated contrast, in the setting of suspected renal calculus, retroperitoneal hematoma, common duct calculus, abdominal aortic aneurysm with or without rupture, and in patients undergoing a PET-CT scan. In the absence of intravenous contrast, vascular structures may prove challenging to evaluate, yet their assessment is an important component of every non-contrast CT examination. We describe the key imaging features of both arterial and venous pathology, and review clues and common associated non-vascular findings, which can help the radiologist identify vascular disorders at non-contrast CT. Briefly, alternative imaging options are discussed.

Plain radiography may underestimate the burden of body packer ingestion: A case report.

Body packing refers to the intracorporeal concealment of illicit drugs. Here we report the case of a 55-year-old body packer who presented with palpitations, visual hallucinations, and a sense of impending death. Abdominal radiography demonstrated five ovoid foreign bodies overlying the rectum. At subsequent gastrotomy and cecotomy, thirty-eight cocaine-containing packets were retrieved from the stomach and ascending colon as well as from the rectum. As the contraband market evolves new techniques to evade detection, evaluation of the burden of body packer ingestion has become increasingly challenging. As demonstrated in this case, plain radiography can grossly underestimate the burden of ingestion.

Small bowel volvulus in pregnancy with associated superior mesenteric artery occlusion.

Here we report the case of a pregnant 28-year-old who presented with acute upper abdominal pain. CT demonstrated midgut volvulus with short segment occlusion of the superior mesenteric artery (SMA). Emergent detorsion of the small bowel was performed, at which time underlying intestinal malrotation was discovered. Following detorsion, the SMA had a bounding pulse and did not require thrombectomy or revascularization. Fewer than 25 cases of midgut volvulus during pregnancy have been reported over the past 20years. To our knowledge, this is the first report of maternal midgut volvulus in which imaging captures the resultant occlusion of the SMA.

Abdominal and pelvic manifestations of Rosai-Dorfman disease: a review of four cases.

Rosai-Dorfman disease is a rare disorder of unknown etiology caused by the proliferation of histiocytes within lymph nodes, predominantly in the cervical chain. Extranodal sites may be involved as well, with involvement of nearly every organ system described in the literature. Abdominal and pelvic manifestations of Rosai-Dorfman disease are extremely rare. We present four cases of abdominal and pelvic involvement by Rosai-Dorfman disease, specifically within the biliary tract, pancreas, spleen, and presacral space. Of note, a presacral mass was present in three of the four patients, and although not previously reported in Rosai-Dorfman disease, may suggest the diagnosis in the proper clinical scenario.

ACR Appropriateness Criteria Staging of Testicular Malignancy.

Testicular cancer represents only 1% of all malignancies occurring in men. However, it is the most frequent malignancy in men between the ages of 20 and 34 years, accounting for 10% to 14% of cancer incidence in that age group. In most instances, the diagnosis of testicular tumors is established with a carefully performed physical examination and scrotal ultrasonography. Tumor markers are useful for determining the presence of residual disease. Cross-sectional imaging studies (CT, MRI) are useful in determining the location of metastases. Chest radiography and CT are used to assess pulmonary disease. Fluorine-18-2-fluoro-2-deoxy-d-glucose (FDG) PET scans have slightly higher sensitivity than CT, but their role in staging testicular cancer has not been determined in a large study. FDG PET may play a role in the follow-up of higher stage seminoma after chemotherapy. Bone scans are useful in the absence of FDG PET scans and should be used when bone metastases are suspected. The ACR Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision include an extensive analysis of current medical literature from peer reviewed journals and the application of well-established methodologies (the RAND/UCLA Appropriateness Method and the Grading of Recommendations Assessment, Development, and Evaluation) to rate the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances in which evidence is lacking or equivocal, expert opinion may supplement the available evidence to recommend imaging or treatment.

An Interesting Cause of Mechanical Small Bowel Obstruction.

Foreign body ingestion is a known cause of abdominal pain in pediatric population occurring between 6 months and 3 years of age (Wyllie Curr Opin Pediatr 18:563, 2006, Uyemura Am Fam Physician 72:287, 2005, Banerjee Indian J Pediatr 72:173, 2005). Most of the ingested foreign bodies pass spontaneously with 10-20 % requiring endoscopic retrieval, and <1 % of cases require a surgical intervention (Wyllie Curr Opin Pediatr 18:563, 2006, Uyemura Am Fam Physician 72:287, 2005, Shivakumar Indian J Pediatr 71:689, 2004). Presence of intestinal obstruction necessitates surgical intervention to extract the ingested foreign body. Initial abdominal plain radiograph should be obtained when foreign body ingestion is suspected, which differentiates a radiopaque from radiolucent foreign bodies. A computed tomography with 3D reconstruction (3D-CT) is recommended with radiolucent foreign bodies (Uyemura Am Fam Physician 72:287, 2005, Kazam Am J Emerg Med 23:897, 2005). After 24 h of expectant management, failure of spontaneous passage requires further intervention. Timely intervention to relieve the obstruction is pivotal to prevent undue complications. We present an interesting case of a boy who ingested a radiolucent foreign body diagnosed on 3D-CT, successfully treated with surgical extraction.

Perforation of the mesenteric small bowel: etiologies and CT findings.

The purpose of this article is to illustrate and discuss the various etiologies of perforation of the mesenteric small bowel and associated findings on abdominal CT. Perforation of the mesenteric small bowel is an uncommon cause of an acute abdomen and can be due to various etiologies. In underdeveloped countries, infection is probably the most common cause, while in industrialized nations, perforation may be due to Crohn disease, diverticulitis, foreign body, trauma, tumor, mechanical obstruction, primary ischemic event, or iatrogenic causes. CT is usually the initial imaging examination in patients with an acute abdomen and is sensitive in diagnosing small bowel perforation. CT findings in the setting of small bowel perforation are often subtle, but when present, may help the radiologist determine a specific cause of perforation. The aims of this pictorial essay are to review the various causes of mesenteric small bowel perforation and to discuss and illustrate the CT findings that can help arrive at the diagnosis.

Dual pathology in a patient with right lower quadrant pain.

Meckel diverticula are remnants of the omphalomesenteric duct. They have 2% incidence in the general population, are usually asymptomatic, and tend to be diagnosed incidentally. The generally held principle had been that asymptomatic cases do not require resection, as exemplified by a 2008 systematic review of over 200 studies. However, a recent series reported an increased risk of malignancies, and recommended mandatory resection. We present a case of Meckel diverticulitis with concurrent infiltrative appendiceal carcinoid in a patient with right lower quadrant pain.

Ectopic pancreas: a diagnostic dilemma.

An ectopic pancreas is defined as pancreatic tissue lacking vascular or anatomic communication with the normal body of the pancreas. It is rarely symptomatic as it is found incidentally at laparotomy most of the time. Despite advances in diagnostic modalities, it still remains a challenge to the clinician to differentiate it from a neoplasm. It is prudent to differentiate it from neoplastic etiologies, as simple surgical excision can potentially be curative. We discuss the presentation, diagnosis, and treatment of an interesting case of ectopic pancreas presenting as a gastric antral tumor.