Origin and stability of exomoon atmospheres: implications for habitability.

We study the origin and escape of catastrophically outgassed volatiles (H2O, CO2) from exomoons with Earth-like densities and masses of 0.1, 0.5 and 1 M⊕ orbiting an extra-solar gas giant inside the habitable zone of a young active solar-like star. We apply a radiation absorption and hydrodynamic upper atmosphere model to the three studied exomoon cases. We model the escape of hydrogen and dragged dissociation products O and C during the activity saturation phase of the young host star. Because the soft X-ray and EUV radiation of the young host star may be up to ~100 times higher compared to today's solar value during the first 100 Myr after the system's origin, an exomoon with a mass < 0.25 M⊕ located in the HZ may not be able to keep an atmosphere because of its low gravity. Depending on the spectral type and XUV activity evolution of the host star, exomoons with masses between ~0.25 and 0.5 M⊕ may evolve to Mars-like habitats. More massive bodies with masses >0.5 M⊕, however, may evolve to habitats that are a mixture of Mars-like and Earth-analogue habitats, so that life may originate and evolve at the exomoon's surface.

Effects of peripheral vascular intervention on ischemia-modified albumin.

Ischemia -modified albumin was regarded as an early marker of cardiac ischemia. On the other hand, it has been reported that increased ischemia-modified albumin levels are associated with unstable plaque processes like percutaneous coronary intervention, acute coronary syndrome or myocardial infarction. This prospective study aimed to investigate the role of ischemia-modified albumin in patients with peripheral vascular disease undergoing peripheral vascular intervention, a plaque-altering procedure without evidence of tissue ischemia. Peripheral vascular intervention was performed in 21 consecutive patients (68.2+/-13.3 years) with typical leg claudication and documented peripheral vascular disease. Additionally, 96 consecutive patients (66+/-12.0 years) undergoing routine exercise stress test for the exclusion of functionally relevant coronary artery disease were defined as controls. It was assumed that in the latter patients no unstable plaque-altering processes were present. Blood samples were drawn before, and 30 min and 3 h after, revascularization in the peripheral vascular intervention group, as well as before, and 30 min and 3 h after, maximum stress testing in the control group, respectively. Ischemia-modified albumin levels were analyzed using the albumin cobalt-binding test. In patients undergoing peripheral vascular intervention, ischemia-modified albumin increased from 116.6+/-19.1 U/ml at baseline to 132.0+/-19.3 U/ml 30 min after intervention (+14.4+/-15.7%, P<0.001) and decreased to 123.5+/-17.8 U/ml 3 h later (-5.7+/-10.5%, P<0.001 compared with postintervention, P<0.001 compared with baseline). The control group showed a slight but significant decrease in ischemia-modified albumin from 103.0+/-11.0 to 100.2+/-11.6 U/ml poststress (-2.2+/-11.5%, P<0.05) and returned close to baseline 3 h later (101.8+/-10.3 U/ml, +2.4+/-10.9%, P=NS, compared with poststress and with baseline). For both groups, ischemia-modified albumin showed no correlation with albumin (at baseline P=0.62) and total protein (P=0.67), but significant correlation with creatinine (P=0.04) and C-reactive protein (P=0.02). In addition, ischemia-modified albumin was independent of age, sex, alanine aminotransferase, aspartate aminotransferase, creatine kinase, creatine kinase-MB, cholesterol, and triglycerides. This study showed an increased basal ischemia-modified albumin level in patients with peripheral vascular disease undergoing peripheral vascular intervention. Ischemia-modified albumin levels transiently increased shortly after peripheral vascular intervention, indicating a strong correlation between serum concentration of ischemia-modified albumin and processes associated with acute plaque disruption/rupture.

Advances in digital radiography: physical principles and system overview.

During the past two decades, digital radiography has supplanted screen-film radiography in many radiology departments. Today, manufacturers provide a variety of digital imaging solutions based on various detector and readout technologies. Digital detectors allow implementation of a fully digital picture archiving and communication system, in which images are stored digitally and are available anytime. Image distribution in hospitals can now be achieved electronically by means of web-based technology with no risk of losing images. Other advantages of digital radiography include higher patient throughput, increased dose efficiency, and the greater dynamic range of digital detectors with possible reduction of radiation exposure to the patient. The future of radiography will be digital, and it behooves radiologists to be familiar with the technical principles, image quality criteria, and radiation exposure issues associated with the various digital radiography systems that are currently available.

Recurrent severe gastrointestinal bleeding and malabsorption due to extensive habitual megacolon.

Dilatation of the colon and the rectum, which is not attributable to aganglionosis, is a rare finding and can be the result of intractable chronic constipation. We report a rare case of a 29-year-old male patient with impressive megacolon, in whom Hirschsprung's or Chagas disease was ruled out. In the present case, dilatation of the colon was most likely due to a behavioral disorder with habitual failure of defecation. Chronic stool retention led to a bizarre bulging of the large bowel with displacement of the other abdominal organs and severe occult blood loss. Because of two episodes of life-threatening gastrointestinal bleeding despite conventional treatment of constipation, a surgical approach for bowel restoration was necessary. Temporary loop ileostomy had to be performed for de-pressurization of the large bowel and the subsequent possibility for effective antegrade colonic lavage to remove impacted stools. Shortly after the operation, the patient was healthy and could easily manage the handling of the ileostomy. However, the course of the megacolon in this young adult cannot be predicted and the follow-up will have to reveal if regression of this extreme colonic distension with reestablishment of regular rectal perception will occur.

Morphological and functional assessment of the septal course of a left coronary artery originating from the right sinus of valsalva in a heart transplant patient.

A septal course of the left main coronary artery originating from the right sinus of Valsalva is a rare coronary anomaly of unknown clinical significance. We report on the morphological and functional assessment of this coronary anomaly detected incidentally in a 53-year-old asymptomatic man after orthotopic heart transplantation.

Renal cell carcinoma in patients with a solitary kidney after nephrectomy treated with radiofrequency ablation: mid term results.

This retrospective study aimed to evaluate the feasibility and effectiveness of radiofrequency ablation (RFA) in patients with solitary kidney for the treatment of renal cell carcinoma (RCC). Within 2 years 10 patients (seven males, three females; age 65+/-8 years) were treated. All patients had a history of nephrectomy of the contralateral kidney. The indications for RFA were inoperability or high probability of complete renal failure after surgical enucleation of the tumor. 13 tumors with a size between 1.9 and 4.2 cm (average 2.7 cm) were treated. In patients with a tumor diameter larger than 2.5 cm a transarterial embolization was performed prior to RFA to reduce heat sink effect and risk of bleeding. Therapeutical success was defined as a lack of contrast enhancement in follow up examinations and shrinking of the treated area. Furthermore all patients' renal function was monitored. RFA of renal tumors under CT-fluoroscopy was feasible in all patients. Within the follow up (3 and 24 months) no tumor recurrence or major complication was detected. One patient developed another RCC and was successfully treated with a second RF-ablation. None of the patients developed renal failure with the need of hemodialysis. In one of the patients a hemorrhage into the surrounding tissue was noticed, which stopped spontaneously. RFA is a valuable and effective therapeutical option in patients with solitary kidney suffering from inoperable renal cell carcinoma. The complication rate is small and an excellent tumor control can be achieved without deterioration of the renal function.

Radiofrequency ablation in the treatment of osteoid osteoma-5-year experience.

PURPOSE: This study aimed to determine the success and complication rates of radiofrequency ablation (RFA) in treatment of osteoid osteoma (OO) and duration of pain relief. Furthermore value of bone biopsy prior to the RFA was evaluated. MATERIALS AND METHODS: Within 61 months 39 patients (23 male, 16 female, 7-53 years, mean 18.7 years, median 17 years) suffering from osteoid osteoma were treated. Lesions were located in femur (n=20), tibia (n=10), spine (n=5), humerus (n=1), radius (n=1), talus (n=1) and pelvis (n=1). In children, RFA was performed under general anaesthesia, in adults conscious sedation was preferred. In 29 of 39 (74%) lesion biopsies were obtained. Cooling of skin was performed in OOs located in bones with minor soft tissue covering (tibia, radius) and saline flushing via an additional needle was performed if the OO was adjacent to nerval structures. Primary success rate, complications, symptom-free interval, follow-up and biopsy results were evaluated. RESULTS: Within observation period (1-61 months; median: 32 months) 38 of 39 patients were successfully treated and had no more complaints. In 3 of 38 patients relapse occurred after 1, 14 and 32 months and RFA was repeated. Two major complications (broken drill, infection) and 2 minor complications (hematoma, prolonged pain) were observed. Biopsy was able to prove diagnosis in 14 of 29 (48%) cases. CONCLUSIONS: Biopsy prior to treatment is not mandatory due to a remarkable amount of false negative findings in clinically and morphologically unambiguous cases of OO. RFA is a highly effective, efficient, minimally invasive and safe method for the treatment of OO.

Radiofrequency ablation in combination with osteoplasty in the treatment of painful metastatic bone disease.

PURPOSE: To evaluate the feasibility and effectiveness of combining radiofrequency (RF) ablation and osteoplasty for pain reduction in the treatment of painful osteolytic metastases. MATERIALS AND METHODS: Within 5 years, 22 patients (15 men and seven women; median age, 64 years) with 28 lesions located in the thoracic and lumbar spine, sacrum, pelvis, acetabulum, femur, and tibia were treated. Underlying tumors were breast, lung, renal cell, thyroid, cancer of unknown primary, and multiple myeloma. RF ablation was performed with the patient under moderate sedation and computed tomographic fluoroscopy guidance and was immediately followed by cement injection. Pain relief was evaluated with the visual analogue scale (VAS) score and the extent to which analgesics could be reduced. Clinical success was defined as a substantial reduction in pain and/or a reduced demand for analgesics, and technical success was defined as distribution of cement between both endplates of a vertebral body or at least 75% filling of osteolyses in other bones. RESULTS: Technical success and pain relief was achieved in all patients. Pain ratings with the VAS decreased from a mean of 8.5 to a mean of 5.5 after 24 hours (P < .01), and a further decrease was detected after 3 months to 3.5 (P < .01). The amount or strength of analgesics was reduced in 15 patients and remained unchanged in five. In two patients, the amount of analgesics increased due to tumor progression elsewhere. No major complication, no clinically obvious fracture of a formerly treated bone or treatment-related death, occurred. CONCLUSIONS: RF ablation and osteoplasty can be combined within one session and is both feasible and useful for the treatment of osteolytic bone metastases with regard to pain relief.

Critical limb ischemia: hybrid MR angiography compared with DSA.

PURPOSE: To compare a hybrid magnetic resonance (MR) angiography protocol with selective digital subtraction angiography (DSA) in patients with critical limb ischemia. MATERIALS AND METHODS: The study was approved by the institutional review board, and written consent was obtained from all patients. Pretreatment DSA and hybrid MR angiography were performed in 19 consecutive patients (15 men, four women; mean age, 69.8 years; range, 44-86 years). Hybrid MR angiography included submillimeter dual-phase three-dimensional gadolinium-enhanced MR angiography in lower calf and foot, and four-station bolus-chase MR angiography in pelvis, thigh, and upper calf. Three readers identified the target lesion and inflow and outflow segments and determined treatment (bypass graft placement, percutaneous transluminal angioplasty, conservative management, amputation). Results of interobserver and intermethod comparisons were expressed as percentage of agreement and 95% confidence interval (CI). RESULTS: On hybrid MR angiograms, no substantial venous overlay was present and image quality was excellent or adequate in 18 (95%) of 19 limbs. Readers 1, 2, and 3 selected the identical target lesion on the DSA image and the MR angiogram in 18, 17, and 18 of 18 comparable limbs, respectively. Mean percentage of agreement for readers 1 and 3 was 100% (95% CI: 81%, 100%) and for reader 2 was 94% (95% CI: 73%, 100%). Agreement of all three readers was superior with use of MR angiography for determination of inflow segments (13 [72%] of 18 limbs) and outflow segments (17 [94%] of 18 limbs), compared with agreement with use of DSA (13 [68%] of 19 inflow segments, 10 [53%] of 19 outflow segments). Agreement in therapy decisions was higher with DSA (15 [79%] of 19) than with MR angiography (11 [61%] of 18). CONCLUSION: Preliminary data strongly support the combination of submillimeter dual-phase MR angiography in lower calf and foot with four-station bolus-chase MR angiography to extend the utility of MR angiography to patients with critical limb ischemia.

High-spatial-resolution MR angiography of renal arteries with integrated parallel acquisitions: comparison with digital subtraction angiography and US.

PURPOSE: To retrospectively compare three-dimensional gadolinium-enhanced magnetic resonance (MR) angiography, performed with an integrated parallel acquisition technique for high isotropic spatial resolution, with selective digital subtraction angiography (DSA) and intravascular ultrasonography (US) for accuracy of diameter and area measurements in renal artery stenosis. MATERIALS AND METHODS: The study was approved by the institutional review board, and consent was obtained from all patients. Forty-five patients (17 women, 28 men; mean age, 62.2 years) were evaluated for suspected renal artery stenosis. Three-dimensional gadolinium-enhanced MR angiograms were acquired with isotropic spatial resolution of 0.8 x 0.8 x 0.9 mm in 23-second breath-hold with an integrated parallel acquisition technique. In-plane diameter of stenosis was measured along vessel axis, and perpendicular diameter and area of stenosis were assessed in cross sections orthogonal to vessel axis, on multiplanar reformations. Interobserver agreement between two radiologists in measurements of in-plane and perpendicular diameters of stenosis and perpendicular area of stenosis was assessed with mean percentage of difference. In a subset of patients, degree of stenosis at MR angiography was compared with that at DSA (n = 20) and intravascular US (n = 11) by using Bland-Altman plots and correlation analyses. RESULTS: Mean percentage of difference in stenosis measurement was reduced from 39.3% +/- 78.4 (standard deviation) with use of in-plane views to 12.6% +/- 9.5 with use of cross-sectional views (P < .05). Interobserver agreement for stenosis grading based on perpendicular area of stenosis was significantly better than that for stenosis grading based on in-plane diameter of stenosis (mean percentage of difference, 15.2% +/- 24.2 vs 54.9% +/- 186.9; P < .001). Measurements of perpendicular area of stenosis on MR angiograms correlated well with those on intravascular US images (r(2) = 0.90). CONCLUSION: Evaluation of cross-sectional images reconstructed from high-spatial-resolution three-dimensional gadolinium-enhanced MR renal angiographic data increases the accuracy of the technique and decreases interobserver variability.