Crystal orientation fabric anisotropy causes directional hardening of the Northeast Greenland Ice Stream.

The dynamic mass loss of ice sheets constitutes one of the biggest uncertainties in projections of ice-sheet evolution. One central, understudied aspect of ice flow is how the bulk orientation of the crystal orientation fabric translates to the mechanical anisotropy of ice. Here we show the spatial distribution of the depth-averaged horizontal anisotropy and corresponding directional flow-enhancement factors covering a large area of the Northeast Greenland Ice Stream onset. Our results are based on airborne and ground-based radar surveys, ice-core observations, and numerical ice-flow modelling. They show a strong spatial variability of the horizontal anisotropy and a rapid crystal reorganisation on the order of hundreds of years coinciding with the ice-stream geometry. Compared to isotropic ice, parts of the ice stream are found to be more than one order of magnitude harder for along-flow extension/compression while the shear margins are potentially softened by a factor of two for horizontal-shear deformation.

Accelerating ice flow at the onset of the Northeast Greenland Ice Stream.

Mass loss near the ice-sheet margin is evident from remote sensing as frontal retreat and increases in ice velocities. Velocities in the ice sheet interior are orders of magnitude smaller, making it challenging to detect velocity change. Here, we analyze a 35-year record of remotely sensed velocities, and a 6-year record of repeated GPS observations, at the East Greenland Ice-core Project (EastGRIP), located in the middle of the Northeast-Greenland Ice Stream (NEGIS). We find that the shear margins of NEGIS are accelerating, indicating a widening of the ice stream. We demonstrate that the widening of the ice stream is unlikely to be a response to recent changes at the outlets of NEGIS. Modelling indicates that the observed spatial fingerprint of acceleration is more consistent with a softening of the shear margin, e.g. due to evolving fabric or temperature, than a response to external forcing at the surface or bed.

Artificial selection for structural color on butterfly wings and comparison with natural evolution.

Brilliant animal colors often are produced from light interacting with intricate nano-morphologies present in biological materials such as butterfly wing scales. Surveys across widely divergent butterfly species have identified multiple mechanisms of structural color production; however, little is known about how these colors evolved. Here, we examine how closely related species and populations of Bicyclus butterflies have evolved violet structural color from brown-pigmented ancestors with UV structural color. We used artificial selection on a laboratory model butterfly, B. anynana, to evolve violet scales from UV brown scales and compared the mechanism of violet color production with that of two other Bicyclus species, Bicyclus sambulos and Bicyclus medontias, which have evolved violet/blue scales independently via natural selection. The UV reflectance peak of B. anynana brown scales shifted to violet over six generations of artificial selection (i.e., in less than 1 y) as the result of an increase in the thickness of the lower lamina in ground scales. Similar scale structures and the same mechanism for producing violet/blue structural colors were found in the other Bicyclus species. This work shows that populations harbor large amounts of standing genetic variation that can lead to rapid evolution of scales' structural color via slight modifications to the scales' physical dimensions.

Skeletal muscle metastases on FDG PET/CT imaging.

BACKGROUND: Skeletal muscle metastases (SMM) are a rare occurrence despite the fact that skeletal muscle comprises more than 50% of total body mass. When present, most are asymptomatic and are often found incidentally on imaging. Several studies have reported isolated cases of patients with SMM. The goal of our study was to perform a comprehensive retrospective analysis of the incidence, frequency, and source of SMM in patients with malignancies who underwent whole-body FDG PET/CT imaging for the workup for their malignancy. METHODS: The records of 8492 consecutive patients referred for oncologic imaging at our institution during the period from January 2006 to December 2009 were reviewed. Patients who had SMM on FDG PET imaging were further assessed for collaborating evidence on other imaging modalities, pathology from tissue sampling, and follow-up scans. The incidence of SMM in our setting was calculated, and their association with various primary malignancies was also evaluated. RESULTS: A total of 73 patients with SMM were identified on PET/CT imaging (incidence, 0.86%). Lung cancer was the most frequent source (25 patients [34%]), followed by gastrointestinal tract malignancies (13 patients [18%]), breast cancer (10 patients [14%]), genitourinary malignancies and lymphoma (6 patients [8%] each), melanoma (5 patients [7%]), and other miscellaneous malignancies (3 patients [4%]). Primary source remained unknown in only 5 patients (7%). Most patients with SMM generally had markedly widespread involvement which led to an unusual appearance on FDG PET/CT imaging. However, since most of these patients had stage IV malignant disease by virtue of visceral metastases elsewhere as well, they were generally not upstaged. CONCLUSIONS: Our study confirmed the rare occurrence of SMM. Furthermore, FDG PET/CT can potentially detect unsuspected SMM. Interestingly, in our patient population, lung cancer was found to be the most frequent malignancy metastasizing to the skeletal muscles. Knowledge about the presence and appearance of widespread SMM may aid in appropriate interpretation of FDG PET/CT scans.

Utility of panendoscopy for the detection of unknown primary head and neck cancer in patients with a negative PET/CT scan.

We conducted a retrospective review of the records of 23 patients who had been diagnosed with regionally metastatic head and neck squamous cell carcinoma from an unknown primary tumor. Our goal was to assess the utility of panendoscopy in locating the primary tumor in those patients whose positron-emission tomography/computed tomography (PET/CT) findings were negative. Overall, we found that PET/CT had correctly identified the unknown primary in 12 of the 23 patients (52%); panendoscopy confirmed this finding in all 12. Of the remaining 11 patients, however, panendoscopy located the primary tumor in only 1 (9%). In this era of cost containment and ongoing advances in imaging and transnasal esophagoscopy, it is important to revisit the workup of an unknown primary in patients with a negative PET/CT scan. There are various advantages and disadvantages to performing panendoscopy with biopsy in patients with an unknown primary and a negative PET/CT scan, but our results and the findings of others indicate that it will detect the primary in only about 10% of these cases. We recommend careful selection of patients who are to undergo panendoscopy for the routine workup of an unknown primary.

18F-FDG PET in pregnancy and fetal radiation dose estimates.

UNLABELLED: The purpose of this study was to estimate the fetal radiation exposure resulting from (18)F-FDG PET procedures performed in pregnant patients with malignancies. METHODS: Five pregnant patients with a biopsy-proven diagnosis of malignancy who underwent (18)F-FDG PET studies were retrospectively reviewed. All patients underwent PET-only studies (and not PET/CT studies) with a reduced (18)F-FDG dose (except for 1 patient who had a negative pregnancy test immediately before the (18)F-FDG PET procedure but was confirmed to be pregnant a few weeks later), including vigorous hydration and diuresis to minimize radiation exposure to the fetus. One patient underwent (18)F-FDG PET twice during her pregnancy (in the second and third trimesters). Fetal radiation dose was independently assessed for each patient, and an analysis was made of fetal radiation doses using the measurements of activity in the fetuses at various stages of pregnancy. RESULTS: Six (18)F-FDG PET studies in 5 pregnant patients were analyzed. The (18)F-FDG PET scans were obtained in early pregnancy (n = 1), the second trimester (n = 2), and the third trimester (n = 3). The fetal dose exposure from (18)F-FDG PET studies was estimated to range from 1.1 to 2.43 mGy for various trimesters in pregnancy (except for the patient in the early stage of pregnancy, in whom activity in the whole uterus was considered, and the fetal dose was estimated to be 9.04 mGy). All patients delivered healthy infants with no visible abnormalities at term. CONCLUSION: The fetal radiation dose from (18)F-FDG PET studies is quite low and significantly below the threshold dose for deterministic effects due to radiation exposure to the fetus. The estimated fetal radiation exposure in our cases was slightly lower than existing estimates on fetal dose exposure, and as more data become available, the current fetal dose estimates may have to be modified accordingly. By addressing an important safety issue dealing with performing medically necessary (18)F-FDG PET in pregnant patients, these data are expected to help in the imaging workup of cancer patients during pregnancy.

FDG PET/CT imaging suggests lymphoma involving prostate may be more resistant to treatment.

FDG PET imaging is generally not useful for prostate cancer. Nevertheless, incidental intense FDG uptake in the prostate warrants further evaluation to assess for prostatic malignancy. We report a case where intense FDG uptake was incidentally noted in an enlarged prostate on FDG PET/CT scan performed for a large left hilar/mediastinal mass (that was also intensely FDG avid along with several additional FDG-avid lesions elsewhere). Biopsy of the prostate and mediastinal lesions revealed large B-cell non-Hodgkin lymphoma at both sites. Serial FDG PET/CT imaging in this patient revealed that the prostatic lymphomatous lesions showed a slower and incomplete response to chemotherapy compared with other sites of lymphomatous involvement (that showed a rapid and complete response to chemotherapy) in the same patient.

Trimodal therapy for inflammatory breast cancer: a surgeon's perspective.

Inflammatory breast cancer (IBC) is a rare and most aggressive form of breast cancer. The onset and progression of disease are rapid; diagnosis must be made expediently to initiate treatment quickly. In this review, the clinical presentation, trimodal therapy, surgical principles and a brief summary of the Louisiana State University at Shreveport experience with IBC are presented. With this aggressive approach, 5-year survival of better than 40-50% can be expected. This represents a substantive improvement in clinical outcome for IBC patients compared with 30 years ago.

Early Detection of Brain Pathology Suggestive of Early AD Using Objective Evaluation of FDG-PET Scans.

The need for early detection of AD becomes critical as disease-modifying agents near the marketplace. Here, we present results from a study focused on improvement in detection of metabolic deficits related to neurodegenerative changes consistent with possible early AD with statistical evaluation of FDG-PET brain images. We followed 31 subjects at high risk or diagnosed with MCI/AD for 3 years. 15 met criteria for diagnosis of MCI, and five met criteria for AD. FDG-PET scans were completed at initiation and termination of the study. PET scans were read clinically and also evaluated objectively using Statistical Parametric Mapping (SPM). Using standard clinical evaluation of the FDG-PET scans, 11 subjects were detected, while 18 were detected using SPM evaluation. These preliminary results indicate that objective analyses may improve detection; however, early detection in at-risk normal subjects remains tentative. Several FDA-approved software packages are available that use objective analyses, thus the capacity exists for wider use of this method for MCI/AD.

Potential value of quantitative analysis of cerebral PET in early cognitive decline.

BACKGROUND: In patients diagnosed with Alzheimer's disease, positron emission tomography brain scans can have characteristic hypometabolic patterns that strongly support this diagnosis, but this pattern is often subtle or absent in early stages. A sensitive and objective method for detection of positron emission tomography abnormalities may have value in early detection of Alzheimer's disease. METHODS: A 2-fluoro-2-deoxy-D-glucose positron emission tomography scans from cognitively impaired patients (n = 43) were compared individually to 28 normal controls using statistical parametric mapping, hypometabolic regions visualized, and clinically correlated. The objective SPM results were compared to the official Nuclear Medicine report based upon subjective interpretation criteria. RESULTS: A total of 22/43 had abnormalities per the Nuclear Medicine physician, while 21/43 appeared normal. The objective analysis detected abnormalities in 41/43 participants, including 19 of 21 that appeared normal. In these 19, 8 had findings consistent with early Alzheimer's disease. CONCLUSION: Objective analysis of positron emission tomography brain scans may extend the ability to detect early brain abnormalities in patients with cognitive decline.

Costosternal chondrodynia simulating recurrent breast cancer unveiled by FDG PET.

FDG-PET imaging, which is routinely used to assess recurrent breast cancer, is nonspecific for malignancies and can detect several inflammatory lesions. Costochondritis following breast reconstructive surgery, presenting with excruciating chest pain or "chondrodynia," is a rare variant of Tietze's syndrome thought to occur due to traction exerted by large breast implants. Diagnosis is usually clinical because no abnormalities are identified on conventional imaging. Two cases have been reported in the literature, but none with FDG-PET. We report a patient with treated breast cancer, presenting with chest pain where FDG-PET to assess for recurrence was consistent with costochondritis and peri-implant inflammation.

Accurate grading of 3 synchronous liposarcomas assessed by PET-CT in a single patient.

Positron emission tomography (PET) with 2-fluoro-deoxyglucose (FDG) has become an established imaging modality that can accurately and noninvasively differentiate malignant neoplasms from benign masses. It is increasingly being used to grade malignant neoplasms as well and has almost replaced other studies like gallium 67-citrate scans for metabolic imaging. We describe an interesting case of 3 synchronous liposarcomas with different radio-opacifications on computed tomography (CT). The more aggressive lesion with more opacity on CT showed intense FDG activity and was found to be a high-grade liposarcoma on pathology. The well-differentiated lesion with more fat content appearing less radio-opaque on CT showed almost no FDG activity and an intermediate grade lesion with intermediate radio-opacity on CT showed mildly increased FDG activity. Dual modality imaging with integrated PET/CT systems have strengthened the confidence of classifying these lesions even before knowing the pathology as depicted in this case.

A Potential Role for F-18 FDG PET/CT in Evaluation and Management of Fibrosing Mediastinitis.

Fibrosing mediastinitis is an uncommon benign disorder, and its pathogenesis and management remain unclear. Conventional imaging techniques (chest radiographs, CT, MRI) may suggest its diagnosis but are frequently nonspecific, and it frequently mimics a malignant process by presenting as a mediastinal mass without calcifications, encasing, and infiltrating adjacent mediastinal structures, and showing an overall aggressive behavior. The value of FDG PET imaging in this entity remains largely unknown with only a few case reports in the literature, and often, biopsy is necessary for definitive diagnosis. We report a case of biopsy proven fibrosing mediastinitis highlighting the utility of PET in the evaluation and management of the disease.

Effect of nicotine and ephedrine on the accumulation of 18F-FDG in brown adipose tissue.

UNLABELLED: This study evaluated the effect of various beta-adrenergic agonists on (18)F-FDG uptake in brown adipose tissue (BAT) in rats using ex vivo biodistribution studies. METHODS: Caffeine (10 mg/kg of body weight, n = 4), ephedrine (5 mg/kg of body weight, n = 4), nicotine (0.8 mg/kg of body weight, n = 9), or a mixture of nicotine and ephedrine (0.8 mg/kg of body weight and 5 mg/kg of body weight, respectively, n = 9) was injected into the peritoneal cavity of female Lewis rats 30 min before intravenous (18)F-FDG injection. One hour after injection of (18)F-FDG, the animals were sacrificed, and BAT, other major organs, and blood were extracted. The biodistribution results were compared with body temperature data. RESULTS: In the rats injected with nicotine or ephedrine, the mean uptake of (18)F-FDG, in percentage injected dose (%ID)/(g of interscapular BAT) x (kg of body weight), was significantly increased (7.9-fold for nicotine and 3.7-fold for ephedrine), compared to the control rats. Nicotine had the strongest effect on (18)F-FDG uptake in BAT. Caffeine increased BAT uptake slightly, but this increase did not reach statistical significance. The combination of nicotine and ephedrine increased the uptake 12.0-fold, compared with control rats; more than either nicotine or ephedrine alone. Uptake of (18)F-FDG in most other major organs did not change significantly. The effect of nicotine was blocked by prior injection of beta-adrenergic antagonists. A transient decrease in body temperature was observed in the nicotine-injected group, and this effect was canceled by prior injection of beta-adrenergic antagonists. No significant change in baseline temperature was seen before or after beta-adrenergic agonist injection. CONCLUSION: Nicotine caused a greater increase in (18)F-FDG uptake in BAT than did other interventions, and the effect was increased when nicotine was combined with ephedrine. The effect of nicotine was completely blocked by prior injection of beta-adrenergic antagonists, indicating that beta-adrenergic agonists increase the metabolism of BAT. These preclinical data suggest that patients should avoid nicotine and ephedrine before undergoing (18)F-FDG PET to minimize (18)F-FDG uptake in BAT.

Reduced presynaptic dopamine activity in fibromyalgia syndrome demonstrated with positron emission tomography: a pilot study.

UNLABELLED: Although the pathophysiology underlying the pain of fibromyalgia syndrome (FMS) remains unknown, a variety of clinical and investigational findings suggests a dysregulation of dopaminergic neurotransmission. We therefore investigated presynaptic dopaminergic function in 6 female FMS patients in comparison to 8 age- and gender-matched controls as assessed by positron emission tomography with 6-[(18)F]fluoro-L-DOPA as a tracer. Semiquantitative analysis revealed reductions in 6-[(18)F]fluoro-L-DOPA uptake in several brain regions, indicating a disruption of presynaptic dopamine activity wherein dopamine plays a putative role in natural analgesia. Although the small sample size makes these findings preliminary, it appears that FMS might be characterized by a disruption of dopaminergic neurotransmission. PERSPECTIVE: An association between FMS and reduced dopamine metabolism within the pain neuromatrix provides important insights into the pathophysiology of this mysterious disorder.

PET imaging today: contribution to the initial staging and prognosis of patients with non-Hodgkin's lymphomas.

Malignant non-Hodgkin lymphomas (NHLs) are commonly staged according to the Ann Arbor staging system developed for Hodgkin's lymphoma. Recently, new staging modalities including metabolic imaging by positron emission tomography (PET) using F-18 fluorodeoxy-glucose (FDG) have been developed. In the present study, we investigated 77 untreated patients with different histologies of NHL both with conventional imaging techniques and FDG-PET. The patients were classified according to the World Health Organization classification and came from 2 major PET imaging centers in Louisiana and Texas. Seventy-six of 77 cases of NHLs were positive by PET imaging. PET imaging resulted, both in high/intermediate grade and indolent NHLs, in a higher stage in more than 20% of cases. In the subtype of high grade NHL diffuse large B cell lymphoma, upstaging by PET appears to be clinically relevant as a marker for a more aggressive tumor. In low grade NHL, stage changes were less pronounced. PET imaging did not reliably detect all cases of bone marrow involvement (especially in indolent lymphomas). However, even in low-grade NHL, clear indications exist for performing PET imaging. The value, the clinical relevance, and new developments in PET imaging for the different types of NHLs are discussed in detail.