The interplay between cosmological expansion and local attraction in a gravitationally bound system is revisited in various regimes. First, weakly gravitating Newtonian systems are considered, followed by various exact solutions describing a relativistic central object embedded in a Friedmann universe. It is shown that the ``all or nothing'' behaviour recently discovered (i.e., weakly coupled systems are comoving while strongly coupled ones resist the cosmic expansion) is limited to the de Sitter background. New exact solutions are presented which describe black holes perfectly comoving with a generic Friedmann universe. The possibility of violating cosmic censorship for a black hole approaching the Big Rip is also discussed.Comment: 17 pages, LaTeX, to appear in Phys. Rev.

Thin-section CT findings usually associated with interstitial lung disease are frequently seen in asymptomatic elderly individuals and are absent in younger subjects. Therefore, these findings may not necessarily represent clinically relevant disease.

The purpose of this study was to describe the range of appearances of adrenal phaeochromocytomas on T2-weighted MRI, correlate appearances with histopathology, and quantify the incidence of the previously described hyperintense appearance. The appearance and MR characteristics of 44 phaeochromocytomas were reviewed retrospectively. T2-weighted appearances were grouped: (1) 'classical', homogeneous, high signal intensity, isointense to CSF; (2) homogeneous, isointense or minimally hyperintense to spleen, hypointense to CSF; (3) heterogeneous, marbled appearance; (4) heterogeneous, multiple high signal intensity pockets. All 44 adrenal phaeochromocytomas were well circumscribed, 1.2-15 cm in maximum diameter, with no visual or quantitative signal loss on chemical shift imaging. On T2-weighted MRI 5/44 (11%) had group 1 appearance; 15/44 (34%) group 2, 7/44 (16%) group 3; and 17/44 (39%) group 4. Homogeneous group 1 and 2 lesions were smaller (mean 4.5 cm) than heterogeneous group 3 and 4 lesions (mean 6.3 cm). Increasing MRI heterogeneity correlated pathologically with increasing amounts of haemorrhage, necrosis and fibrosis. No MRI features were predictive of malignancy. Non-functioning phaeochromocytomas were larger than functioning lesions. No size difference was seen between syndrome and sporadic lesions. In this large series we report a wide range of appearances of adrenal phaeochromocytomas on T2-weighted MRI. The previously described classical hyperintense phaeochromocytoma is relatively uncommon.

Pheochromocytoma (PC) and paraganglioma (PGL) are rare neuroendocrine tumors that occur throughout the body from the base of the skull to the pelvis. Sympathetic catecholamine-secreting tumors may be associated with hyperadrenergic symptoms and longterm morbidity if they are untreated. Typically biochemically silent, head and neck PGLs may result in cranial nerve palsies and symptoms due to localized mass effect. Tumors can arise sporadically or as part of an inheritable PC-PGL syndrome. Up to 40% of tumors are recognized to be associated with germline mutations in an increasing array of susceptibility genes, including those that appear to arise sporadically. Most commonly, up to 25% of all PC-PGLs are associated with mutations in one of the succinate dehydrogenase (SDH) enzyme subunit genes. The resulting familial PC-PGL syndrome varies according to the affected enzyme subunit (most commonly SDHB and SDHD mutations) with respect to tumor prevalence, location, age of onset, and risk of malignancy. Patients with SDH enzyme mutations have increased lifetime risk of developing multifocal tumors and malignancy. Early recognition of individuals at high risk, genetic testing, screening of family members, and lifelong surveillance programs are recommended, but not without health, economic, and psychologic implications. Anatomic and functional imaging is key to diagnosis, staging, treatment planning, and lifelong surveillance of these individuals. Radiologists must be aware of the imaging appearance of these varied tumors. ©

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BackgroundTumour recurrence following oesophagectomy for oesophageal cancer is common despite neoadjuvant treatment. Understanding patterns of recurrence and risk factors associated with locoregional and systemic recurrence might influence future treatment strategies.MethodsThis was a cohort study involving patients undergoing resection for adenocarcinoma or squamous cell carcinoma of the oesophagus between 2000 and 2014. Clinicopathological factors associated with locoregional and systemic recurrence were analysed using multivariable logistic regression to determine odds ratios (ORs) and 95 per cent confidence intervals.ResultsSome 698 patients were identified. Lymphovascular invasion (OR 2·09, 95 per cent c.i. 1·18 to 3·71) and preoperative stenting (OR 3·70, 1·34 to 10·23) were independent risk factors for isolated locoregional recurrence. Pathological nodal disease in patients with pT1–2 (pN1: OR 2·72, 1·35 to 5·48; pN2–3: OR 5·00, 2·35 to 10·66) or pT3–4 (pN1: OR 3·03, 1·51 to 6·07; pN2–3: OR 5·75, 3·15 to 10·49) disease predisposed to systemic recurrence. Poor or no response to chemotherapy was also an independent risk factor for isolated systemic recurrence (OR 1·85, 1·05 to 3·26). A positive resection margin (R1 resection) was not associated with a significantly increased risk of isolated locoregional recurrence (OR 1·37, 0·81 to 2·33).ConclusionThese findings confirm that oesophageal adenocarcinoma is frequently a systemic disease. Understanding the key predictors of local and systemic recurrence may facilitate the tailoring of oncological therapies to the individual patient.

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Background 18F-fluorodeoxyglucose positron emission tomography/magnetic resonance imaging (18F-FDG PET/MRI) may improve cancer staging by combining sensitive cancer detection with high-contrast resolution and detail. We compared the diagnostic performance of 18F-FDG PET/MRI to 18F-fluorodeoxyglucose positron emission tomography/computed tomography (18F-FDG PET/CT) for staging oesophageal/gastro-oesophageal cancer. Following ethical approval and informed consent, participants with newly diagnosed primary oesophageal/gastro-oesophageal cancer were enrolled. Exclusions included prior/concurrent malignancy. Following 324 ± 28 MBq 18F-FDG administration and 60-min uptake, PET/CT was performed, immediately followed by integrated PET/MRI from skull base to mid-thigh. PET/CT was interpreted by two dual-accredited nuclear medicine physicians and PET/MRI by a dual-accredited nuclear medicine physician/radiologist and cancer radiologist in consensus. Per-participant staging was compared with the tumour board consensus staging using the McNemar test, with statistical significance at 5%. Results Out of 26 participants, 22 (20 males; mean ± SD age 68.8 ± 8.7 years) completed 18F-FDG PET/CT and PET/MRI. Compared to the tumour board, the primary tumour was staged concordantly in 55% (12/22) with PET/MRI and 36% (8/22) with PET/CT; the nodal stage was concordant in 45% (10/22) with PET/MRI and 50% (11/22) with PET/CT. There was no statistical difference in PET/CT and PET/MRI staging performance (p > 0.05, for T and N staging). The staging of distant metastases was concordant with the tumour board in 95% (21/22) with both PET/MRI and PET/CT. Of participants with distant metastatic disease, PET/MRI detected additional metastases in 30% (3/10). Conclusion In this preliminary study, compared to 18F-FDG PET/CT, 18F-FDG PET/MRI showed non-significant higher concordance with T-staging, but no difference with N or M-staging. Additional metastases detected by 18F-FDG PET/MRI may be of additive clinical value.