Morphology of the distal thoracic duct and the right lymphatic duct in different head and neck pathologies: an imaging based study.

BACKGROUND: The purpose of this study was to assess the influence of head and neck pathologies on the detection rate, configuration and diameter of the thoracic duct (TD) and right lymphatic duct (RLD) in computed tomography (CT) of the head and neck. METHODS: One hundred ninety-seven patients were divided into the subgroups "healthy", "benign disease" and "malignant disease". The interpretation of the images was performed at a slice thickness of 3 mm in the axial and coronal plane. In each case we looked for the distal part of the TD and RLD respectively and subsequently evaluated their configuration (tubular, sacciform, dendritic) as well as their maximum diameter and correlated the results with age, gender and diagnosis group. RESULTS: The detection rate in the study population was 81.2 % for the TD and 64.2 % for the RLD and did not differ significantly in any of the subgroups. The predominant configuration was tubular. The configuration distribution did not differ significantly between the diagnosis groups. The mean diameter of the TD was 4.79 ± 2.41 mm and that of the RLD was 3.98 ± 1.96 mm. No significant influence of a diagnosis on the diameter could be determined. CONCLUSIONS: There is no significant influence of head/neck pathologies on the CT detection rate, morphology or size of the TD and RLD. However our study emphasizes that both the RLD and the TD are detectable in the majority of routine head and neck CTs and therefore reading physicians and radiologists should be familiar with their various imaging appearances.

Influence of Cardiac MR Imaging on DNA Double-Strand Breaks in Human Blood Lymphocytes.

PURPOSE: To evaluate the ability of magnetic resonance (MR) imaging to induce deoxyribonucleic acid (DNA) damage in patients who underwent cardiac MR imaging in daily routine by using γ-H2AX immunofluorescence microscopy. MATERIALS AND METHODS: This study complies with the Declaration of Helsinki and was performed according to local ethics committee approval. Informed patient consent was obtained. Blood samples from 45 patients (13 women, 32 men; mean age, 50.3 years [age range, 20-89 years]) were obtained before and after contrast agent-enhanced cardiac MR imaging. MR imaging-induced double-strand breaks (DSBs) were quantified in isolated blood lymphocytes by using immunofluorescence microscopy after staining the phosphorylated histone variant γ-H2AX. Twenty-nine patients were examined with a myocarditis protocol (group A), 10 patients with a stress-testing protocol (group B), and six patients with flow measurements and angiography (group C). Paired t test was performed to compare excess foci before and after MR imaging. RESULTS: The mean baseline DSB level before MR imaging and 5 minutes after MR imaging was, respectively, 0.116 DSB per cell ± 0.019 (standard deviation) and 0.117 DSB per cell ± 0.019 (P = .71). There was also no significant difference in DSBs in these subgroups (group A: DSB per cell before and after MR imaging, respectively, 0.114 and 0.114, P = .91; group B: DSB per cell before and after MR imaging, respectively, 0.123 and 0.124, P = .78; group C: DSB per cell before and after MR imaging, respectively, 0.114 and 0.115, P = .36). CONCLUSION: By using γ-H2AX immunofluorescence microscopy, no DNA DSBs were detected after cardiac MR imaging.

Influence of Different Antioxidants on X-Ray Induced DNA Double-Strand Breaks (DSBs) Using γ-H2AX Immunofluorescence Microscopy in a Preliminary Study.

BACKGROUND: Radiation exposure occurs in X-ray guided interventional procedures or computed tomography (CT) and γ-H2AX-foci are recognized to represent DNA double-strand breaks (DSBs) as a biomarker for radiation induced damage. Antioxidants may reduce the induction of γ-H2AX-foci by binding free radicals. The aim of this study was to establish a dose-effect relationship and a time-effect relationship for the individual antioxidants on DSBs in human blood lymphocytes. MATERIALS AND METHODS: Blood samples from volunteers were irradiated with 10 mGy before and after pre-incubation with different antioxidants (zinc, trolox, lipoic acid, ß-carotene, selenium, vitamin E, vitamin C, N-acetyl-L-cysteine (NAC) and Q 10). Thereby, different pre-incubation times, concentrations and combinations of drugs were evaluated. For assessment of DSBs, lymphocytes were stained against the phosphorylated histone variant γ-H2AX. RESULTS: For zinc, trolox and lipoic acid regardless of concentration or pre-incubation time, no significant decrease of γ-H2AX-foci was found. However, ß-carotene (15%), selenium (14%), vitamin E (12%), vitamin C (25%), NAC (43%) and Q 10 (18%) led to a significant reduction of γ-H2AX-foci at a pre-incubation time of 1 hour. The combination of different antioxidants did not have an additive effect. CONCLUSION: Antioxidants administered prior to irradiation demonstrated the potential to reduce γ-H2AX-foci in blood lymphocytes.

Successful treatment of a patient with middle aortic syndrome and renovisceral involvement using aorto-aortic bypass: case report and review of recent literature.

Middle aortic syndrome (MAS), defined as localized abdominal or thoracic aortic hypoplasia, represents an extraordinary rare condition, often diagnosed in younger patients with severe renal hypertension. Etiology is divided into congenital and acquired causes (e.g., Takayasu disease). Because of its extremely unfavorable course, treatment of symptomatic patients is mandatory, whereas open surgery with aorto-aortic bypass or patch aortoplasty is considered the standard therapy. This report describes a case of a 19-year-old Macedonian woman presenting with MAS and renal hypertension who was successfully treated with aorto-aortic bypass, including reconstruction of both renal and the hepatic and superior mesenteric arteries, and reviews the current literature.

X-ray induced formation of γ-H2AX foci after full-field digital mammography and digital breast-tomosynthesis.

PURPOSE: To determine in-vivo formation of x-ray induced γ-H2AX foci in systemic blood lymphocytes of patients undergoing full-field digital mammography (FFDM) and to estimate foci after FFDM and digital breast-tomosynthesis (DBT) using a biological phantom model. MATERIALS AND METHODS: The study complies with the Declaration of Helsinki and was performed following approval by the ethic committee of the University of Erlangen-Nuremberg. Written informed consent was obtained from every patient. For in-vivo tests, systemic blood lymphocytes were obtained from 20 patients before and after FFDM. In order to compare in-vivo post-exposure with pre-exposure foci levels, the Wilcoxon matched pairs test was used. For in-vitro experiments, isolated blood lymphocytes from healthy volunteers were irradiated at skin and glandular level of a porcine breast using FFDM and DBT. Cells were stained against the phosphorylated histone variant γ-H2AX, and foci representing distinct DNA damages were quantified. RESULTS: Median in-vivo foci level/cell was 0.086 (range 0.067-0.116) before and 0.094 (0.076-0.126) after FFDM (p = 0.0004). In the in-vitro model, the median x-ray induced foci level/cell after FFDM was 0.120 (range 0.086-0.140) at skin level and 0.035 (range 0.030-0.050) at glandular level. After DBT, the median x-ray induced foci level/cell was 0.061 (range 0.040-0.081) at skin level and 0.015 (range 0.006-0.020) at glandular level. CONCLUSION: In patients, mammography induces a slight but significant increase of γ-H2AX foci in systemic blood lymphocytes. The introduced biological phantom model is suitable for the estimation of x-ray induced DNA damages in breast tissue in different breast imaging techniques.

The effect of calyculin A on the dephosphorylation of the histone γ-H2AX after formation of X-ray-induced DNA double-strand breaks in human blood lymphocytes.

PURPOSE: The purpose of this study was to investigate the effect of calyculin A on the number of γ-H2AX foci (phosphorylated histone variant 2AX) in lymphocytes after in vitro and in vivo irradiation with rather low doses as they are used in diagnostic and interventional radiology. MATERIALS AND METHODS: For in vitro experiments blood samples of 14 healthy volunteers were irradiated with different doses (10, 50, 100 mGy) and incubated with (0.01, 0.1, 1, 10 nM) or without calyculin A for up to 2 hours. Non-irradiated samples with and without calyculin A served as controls. For in vivo evaluation blood samples were collected from seven patients undergoing computed tomography (CT) both with 1 nM calyculin A containing vials and vials without calyculin A. Foci were quantified in isolated lymphocytes using γ-H2AX immunofluorescence microscopy. RESULTS: 1 nM calyculin A led to a complete inhibition of γ-H2AX foci loss in irradiated samples whereas no inhibition of p53 binding protein 1 (53 BP1) foci was found. Lower concentrations of the phosphatase inhibitor did not have a sufficient effect on foci decrease. Calyculin A did not affect foci levels in non-irradiated samples. If no calyculin A was added into the vial before the blood draws detectable CT-induced foci levels were lower in all patients with a reduction of the medians of 35%. CONCLUSIONS: Using γ-H2AX immunofluorescence microscopy calyculin A can be a useful tool to mark the induced γ-H2AX foci after low dose irradiation and to avoid an underestimation of the real deoxyribonucleic acid (DNA) damage in in vitro and in vivo experiments.

MRI-guided core biopsy of the prostate in the supine position--introduction of a simplified technique using large-bore magnet systems.

OBJECTIVES: To introduce a simplified technique for MRI-guided core biopsies (MRGB) of the prostate in the supine position using large-bore magnet systems. METHODS: Fifty men with a history of negative transrectal ultrasound-guided biopsies underwent MRGB in either a 1.5-T (13/50) or 3.0-T (37/50) wide-bore MRI unit. MRGBs were conducted with the patients in a supine position using a dedicated MR-compatible biopsy device. RESULTS: We developed a dedicated positioning device for the supine position. Using this device, the biopsies were performed successfully in all patients. Apart from minor rectal bleeding, only one patient developed a major side effect (urosepsis). Histology revealed prostate cancer in 25/50 (50 %) patients. CONCLUSIONS: The new technique appears feasible. Its major advantage is the more comfortable and patient-friendly supine position during the biopsy without the need to modify the MRI system's patient table. KEY POINTS: • A novel positioning device for MRI-guided prostate biopsies has been developed. • Biopsies can be performed in the patient-friendly supine position. • The positioning device can be utilised without modifying the MRI's patient table.

Induction and repair of DNA double-strand breaks in blood lymphocytes of patients undergoing ¹8F-FDG PET/CT examinations.

PURPOSE: The purpose of this study was to evaluate DNA double-strand breaks (DSBs) in blood lymphocytes of patients undergoing positron emission tomography (PET)/CT using γ-H2AX immunofluorescence microscopy and to differentiate between (18)F-fluorodeoxyglucose (FDG) and CT-induced DNA lesions. METHODS: This study was approved by the local Ethics Committee and complies with Health Insurance Portability and Accountability Act (HIPAA) requirements. After written informed consent was obtained, 33 patients underwent whole-body (18)F-FDG PET/CT (3 MBq/kg body weight, 170/100 reference mAs at 120 kV). The FDG PET and CT portions were performed as an initial CT immediately followed by the PET. Blood samples were obtained before, at various time points following (18)F-FDG application and up to 24 h after the CT scan. Distinct foci representing DSBs were quantified in isolated lymphocytes using fluorescence microscopy after staining against the phosphorylated histone variant γ-H2AX. RESULTS: The DSB values at the various time points were significantly different (p < 0.001). The median baseline level was 0.08/cell (range 0.06-0.12/cell). Peaks of radiation-induced DSBs were found 30 min after (18)F-FDG administration (median excess foci 0.11/cell, range 0.06-0.27/cell) and 5 min after CT (median excess foci 0.17/cell, range 0.05-0.54/cell). A significant correlation between CT-induced DSBs and dose length product was obtained (ρ = 0.898, p < 0.001). After 24 h DSB values were still slightly but significantly elevated (median foci 0.11/cell, range 0.10-0.14/cell, p = 0.003) compared to pre-exposure levels. CONCLUSION: PET/CT-induced DSBs can be monitored using γ-H2AX immunofluorescence microscopy. Peak values may be obtained 30 min after (18)F-FDG injection and 5 min after CT. The radionuclide contributes considerably to the total DSB induction in this setting.

Normalized metal artifact reduction in head and neck computed tomography.

OBJECTIVE: Artifacts from dental hardware affect image quality and the visualization of lesions in the oral cavity and oropharynx in computed tomography (CT). Therefore, magnetic resonance imaging is considered the imaging modality of choice in this region. Standard methods for metal artifact reduction (MAR) in CT replace the metal-affected raw data by interpolation, which is prone to new artifacts. We developed a generalized normalization technique for MAR (NMAR) that aims to suppress algorithm-induced artifacts and validated the performance of this algorithm in a clinical trial. MATERIAL AND METHODS: A 3-dimensional forward projection identifies the metal-affected raw data in the original projections after metal is segmented in the image domain by thresholding. A prior image is used to normalize the projections before interpolation. The original raw data are divided pixel-wise by the projection data of the prior image and, after interpolation, are denormalized again. Data from 19 consecutive patients with metal artifacts from dental hardware were reconstructed with standard filtered backprojection (FBP), linear interpolation MAR (LIMAR), and NMAR. The image quality of slices containing metal was analyzed for the severity of artifacts and diagnostic value; magnetic resonance imaging performed the same day on a 3-T system served as a reference standard in all cases. RESULTS: A total of 260 slices containing metal dental hardware were analyzed. A total of 164 slices were nondiagnostic with FBP, 157 slices with LIMAR, and 87 slices with NMAR. The mean (SD) number of slices per patient with severe artifacts was 10.1 (3.7), 9.6 (4.6), and 5.4 (3.6) and the mean (SD) number of slices with artifacts affecting diagnostic confidence was 3.3 (1.7), 4.9 (2.9), and 3.7 (1.9) for FBP, LIMAR, and NMAR, respectively (P < 0.001). Pairwise comparison did not show significant differences between FBP and LIMAR (P = 0.40), but there were significant differences between FBP and NMAR as well as LIMAR and NMAR (both P < 0.001). Interobserver agreement was excellent (κ = 0.974). Two malignant lesions were unmasked with NMAR image reconstructions. No algorithm-related artifacts were detected in regions that did not contain metal in NMAR images. CONCLUSION: Normalized MAR has the potential to improve image quality in patients with artifacts from dental hardware and to improve the diagnostic accuracy of CT of the oral cavity and oropharynx.

Effect of antioxidants on X-ray-induced γ-H2AX foci in human blood lymphocytes: preliminary observations.

PURPOSE: To investigate the effect of a radioprotective oral agent containing a formulation of antioxidants and glutathione-elevating compounds on the extent of x-ray-induced γ-H2AX foci formation. MATERIALS AND METHODS: The study was approved by local ethics committee and informed consent was obtained from each subject. In vitro experiments with blood lymphocytes of 25 healthy volunteers were performed without antioxidants and with antioxidants added either before or immediately after irradiation (10 mGy). For in vivo/in vitro tests, blood samples were obtained before, 15, 30, and 60 minutes (n=17) after, and 2, 3, and 5 hours (n=11) after oral ingestion of antioxidant pills and were irradiated (10 mGy). DNA double-strand breaks (DSBs) were quantified in isolated lymphocytes 5 minutes (in vitro and in vivo/in vitro) and 15 minutes (in vitro) after irradiation by enumerating γ-H2AX foci. To validate the data, additional in vitro experiments with use of 53BP1 as another independent marker for DSBs were performed. Nonirradiated samples served as controls. Statistical analyses were performed by using Wilcoxon rank-sum tests (in vitro), repeated-measures test, and Dunnett test (in vivo/in vitro). RESULTS: In the in vitro experiments, 15-minute preincubation with antioxidants significantly reduced mean γ-H2AX foci levels by 23% (P<.0001), whereas addition of antioxidants immediately after irradiation did not lead to a reduction of x-ray-induced foci (P=.6905). Mean 53BP1 foci were also reduced by preincubation with the radioprotectant. In the in vivo/in vitro tests, oral pretreatment with antioxidants also led to a significant reduction of γ-H2AX foci formation; administration 60 minutes before irradiation resulted in a mean foci reduction of 58% (P<.0001). CONCLUSION: The tested formulation of antioxidants significantly reduced formation of γ-H2AX and 53BP1 foci after irradiation at a radiologic radiation dose typical for computed tomographic imaging; administration 60 minutes prior to irradiation seems to be appropriate and leads to a significant reduction in foci.

X-ray induced DNA double-strand breaks in coronary CT angiography: comparison of sequential, low-pitch helical and high-pitch helical data acquisition.

BACKGROUND: Aim of this study was to compare DNA double-strand breaks (DSBs) in blood lymphocytes of patients undergoing high-pitch helical, low-pitch helical and sequential coronary CT angiography. METHODS AND RESULTS: 66 patients were examined with various scan protocols and modes (low-pitch helical scan: 100-120 kV, 320-438 mAs/rot, pitch 0.18-0.39, with or without ECG-pulsing, n=35; prospectively ECG-triggered high-pitch helical scan: 100-120 kV, 320-456 mAs/rotation, pitch 3.2-3.4, n=19; prospectively ECG-triggered sequential scan: 100-120 kV, 150-300 mAs or 320-370 mAs/rotation, n=12) either using a 64-slice or 128-slice dual-source CT or a 128-slice single source CT scanner. Blood samples were obtained before and 30 min after CT and DSBs were analyzed in isolated lymphocytes using γ-H2AX immunofluorescence microscopy. A significant increase of DSBs was measurable 30 min after CTA (range 0.01-0.71/cell). CT induced DSBs showed a significant correlation with the estimated effective dose (ρ=0.90, p<0.00001). Both prospectively ECG-triggered sequential (0.10 DSBs/cell, 176 mGy cm, p<0.00001) and high-pitch helical scan protocols (0.03 DSBs/cell, 109 mGy cm, p<0.00001) led to a significant reduction of median DLP and DSB levels compared to low-pitch helical scans (0.34 DSBs/cell, 828 mGy cm). A reduction of the tube voltage resulted in significantly lower whereas additional calcium scoring resulted in elevated DLP and DNA damages (p<0.05 each). CONCLUSION: In coronary CTA, data acquisition protocols have a significant influence on the X-ray induced DSB levels. Using γ-H2AX immunofluorescence microscopy different scan modes in different CT generations can be compared concerning their biological impact.

Reduction of X-ray induced DNA double-strand breaks in blood lymphocytes during coronary CT angiography using high-pitch spiral data acquisition with prospective ECG-triggering.

OBJECTIVES: Purpose of this study was to compare the effect of high-pitch spiral data acquisition with prospective electrocardiography (ECG)-triggering on the x-ray induced DNA damages to blood lymphocytes with commonly used low-pitch spiral scans. MATERIALS AND METHODS: Thirty four patients underwent coronary computed tomography angiography either using high-pitch spiral data acquisition (n = 15; dual-source computed tomography (CT) scanner, 38.4 mm collimation, 100-120 kV, 320-456 mAs/rotation, pitch value 3.2-3.4) or using a low-pitch protocol (n = 19; dual-source CT scanner, 19.2 mm collimation, 120 kV, 330-438 mAs/rotation, pitch 0.2-0.39, ECG-based tube current modulation). Blood samples were obtained before and 30 minutes after CT. Lymphocytes were isolated, stained against the phosphorylated histone variant gammaH2AX, and DNA double-strand breaks (DSBs) were visualized using fluorescence microscopy. Radiation dose to the blood was estimated by relating in vivo DSB levels to values of in vitro irradiated blood samples (50 mGy). Dose length product was registered as provided by the patient protocol. RESULTS: Total dose length product ranged from 101 to 237 (median 112) mGy cm in high-pitch and from 524 to 1283 (median 1025) mGy cm in low-pitch scans (P < 0.0001). The median CT induced DSB level 30 minutes after exposure was significantly lower after high-pitch (0.04 DSBs/cell, range 0.02-0.10 DSBs/cell) compared with low-pitch scans (0.39 DSBs/cell, 0.22-0.71 DSBs/cell, P < 0.0001). Both DSB levels and radiation dose to the blood showed a significant correlation to the dose length product (r = 0.82, P < 0.0001). The radiation dose to the blood was significantly reduced in the high-pitch (median 3.1, range 2.0-8.1 mGy) compared with the low-pitch group (median 26.9; range 14.2-44.9 mGy, P < 0.0001). CONCLUSIONS: Prospectively ECG-triggered high-pitch spiral data acquisition can considerably reduce the radiation dose to the blood in coronary CT angiography as compared with low pitch protocols.

An unusual case of hyponatraemia.

The differential diagnosis of hyponatraemia is manifold and includes hormonal disorders such as primary adrenal insufficiency or hypothyroidism. The diagnosis of adrenal insufficiency is always suggestive in cases of hypotension associated with hyponatraemia, hyperkalaemia and metabolic acidosis. We herein report a case of severe hyponatraemia in a patient with Addison's disease. The underlying cause was disseminated adrenal tuberculosis without any evidence of other organ involvement. To date, tuberculosis remains a frequent cause of adrenal insufficiency although the pathophysiology of adrenal tropism is poorly understood.

Peripheral intravenous power injection of iodinated contrast media: the impact of temperature on maximum injection pressures at different cannula sizes.

RATIONALE AND OBJECTIVES: Modern computed tomographic scanners and examination protocols often require high injection rates of iodinated contrast media (CM). The purpose of this study was to investigate the maximum injection pressures (MIPs) with different CM at different temperatures in the most common intravenous cannula (IVC) sizes. MATERIALS AND METHODS: Three IVC sizes, 22, 20, and 18 gauge, were evaluated. All examinations were performed with a pressure-limited (300 psi) power injector. The MIPs of three different CM (Solutrast 300, Imeron 350, and Imeron 400) were measured at room temperature (20 degrees C) and at 37 degrees C using increasing flow rates (1-9 mL/s). The intactness of the IVCs was checked after injection. RESULTS: Heating the CM led to reductions in injection pressures (P < .001). Using constant flow rates, the difference in MIP between 20-gauge and 22-gauge IVCs was higher than that between 20-gauge and 18-gauge IVCs. By heating the CM, the manufacturer's suggested operating pressure limit was exceeded at higher flow rates, such as with an 18-gauge cannula at 8 mL/s instead of 6 mL/s using warmed iomeprol 400. Even with pressures of up to 159.7 psi, none of the IVCs ruptured. CONCLUSIONS: Heating of CM effectively reduces MIPs using power injection in common IVCs. Although the manufacturer's suggested MIP was exceeded at higher flow rates, safe CM injection seems to be possible even in small cannulas using power injection. The compilation of the obtained data is meant to serve as guidance for future decisions on parameters of the power injection of iodinated CM.

Contrast medium-enhanced radiation damage caused by CT examinations.

PURPOSE: To assess the effect of iodinated contrast medium (CM) on the induction and repair of DNA double-strand breaks (DSBs) in peripheral blood lymphocytes after computed tomographic (CT) examinations. MATERIALS AND METHODS: This prospective study was approved by the institutional ethics committee; written informed patient consent was obtained from 37 patients. Venous blood samples were taken from patients before and at 30 minutes, 1 hour, 2.5 hours, and 5 hours after performing CT with (n = 18) or without (n = 19) intravenous administration of CM (iopromide or iomeprol). DSBs were assessed in lymphocytes by enumerating gammaH2AX foci. DSB levels after CT were compared with those obtained after in vitro irradiation. Cell culture experiments with peripheral lymphocytes and fibroblasts were performed with iopromide, iomeprol, or the control substance mannitol added before or immediately after x- or gamma-ray irradiation. DSBs were assessed at 5 minutes, 30 minutes, 2.5 hours, and 5 hours after irradiation. Data were analyzed by using linear regression and the one-tailed Welch and paired sample t tests. RESULTS: The presence of CM during CT increases DSB levels in peripheral lymphocytes by approximately 30%. Cell culture experiments confirmed this effect and further showed that CM administered prior to x-ray irradiation increases the initial DSB yield but has no effect if added after irradiation or when gamma-rays are used instead of x-rays. CONCLUSION: The highly sensitive gammaH2AX foci assay shows that CM-enhanced radiation damage incurred in peripheral lymphocytes during CT. However, it is unknown whether long-term bioeffects of low-dose ionizing radiation from CT examinations, such as cancer, are increased by using CM.

A retrospective study of enteroclysis in patients with manifest food allergy.

PURPOSE: The aim of this study was to investigate whether there are typical findings in enteroclysis of patients suffering from food allergy (FA). MATERIALS AND METHODS: Findings of enteroclysis of 26 FA patients were correlated with results of endoscopic and histologic examinations. In two patients allergen provocation was performed during enteroclysis. RESULTS: No specific mucosal pathologies were found without provocation. After provocation, low mucosal contrast adhesion was observed. CONCLUSION: Without provocation no specific alterations were found. However, enteroclysis may be used for monitoring of allergen challenge.

DNA double-strand breaks and their repair in blood lymphocytes of patients undergoing angiographic procedures.

OBJECTIVES: To adapt gamma-H2AX immunofluorescence microscopy to assessment of induction and repair of DNA double-strand breaks (DSBs) in peripheral blood lymphocytes in patients undergoing angiographic procedures. MATERIALS AND METHODS: The study was approved by the institutional ethics committee. After written informed patient consents were obtained, venous blood samples were taken from 19 patients (age 23-88 years) undergoing different angiographic procedures before, during, and after (10 minutes-24 hours) the examination. Individual DSB yields were visualized by detecting the phosphorylated variant of the histone H2AX (gamma-H2AX) in lymphocytes using fluorescence microscopy. Values were correlated with dose area product. Single in vitro irradiation with 50 mGy was performed in 14 and additional fractionated irradiation with 10 x 5 mGy over a time period corresponding to the angiography duration in 4 patients. The radiation doses to the blood delivered during angiography were estimated by comparing the number of DSBs after angiography with DSB yields obtained after in vitro irradiation. RESULTS: In all patients in vivo and in vitro irradiation increased the number of DSBs (0.03-1.50 per cell), even if very small doses were applied (minimum 338 microGy x m). Thereafter in both in vitro and in vivo a rapid loss of gamma-H2AX foci was observed. The number of DSBs showed a linear correlation to dose area product for specific examination regions (eg, R = 0.85, pelvic and leg arteries). Calculated radiation doses to blood delivered during angiography ranged from 2.2 to 99.9 mGy and increased if fractioned in vitro samples were used as calibration instead of single in vitro irradiations at the same total dose. CONCLUSIONS: gamma-H2AX immunofluorescence microscopy is a reliable and sensitive method for measuring the induction and repair of DNA damage caused by ionizing radiation during angiography. To estimate radiation doses delivered during procedures and to consider patients individual repair capacity, postangiography DSB-yields should be compared with DSB-yields after fractioned in vitro irradiation imitating examination conditions.

Influence of magnetic resonance contrast media on the activity of histamine inactivating enzymes.

RATIONALE AND OBJECTIVES: The observation that the intravenous application of gadolinium-based contrast media can lead to nephrogenic systemic fibrosis (NSF) has raised interest in their interactions with pathways. In this context, histamine is a focus because of its stimulating effect on fibrogenesis. In humans, histamine can be inactivated either by diamine oxidase (DAO) or by histamine N-methyltransferase (HMT), and numerous drugs are known to inhibit these enzymes. Therefore, it was the aim of this study to investigate whether magnetic resonance imaging contrast agents have an inhibitory effect on the enzymatic activities of DAO and HMT. MATERIALS AND METHODS: Seven gadolinium-based (gadoterate meglumine, gadoteridol, gadobutrol, gadobenate dimeglumine, gadopentetate dimeglumine, gadoxetate disodium, gadodiamide) and one manganese-containing (mangafodipir) contrast agents were tested in vitro. Following the preincubation of purified DAO and HMT with 0.1 to 10 mmol/L of the respective contrast medium, enzyme activities were determined using radiometric microassays. Enzyme activities measured in the absence of contrast agents and after preincubation with specific inhibitors of DAO and HMT, respectively, served as controls. RESULTS: The gadolinium-containing and manganese-containing contrast media tested did not show significant inhibition of the activities of DAO and HMT. No significant difference was observed between ionic and nonionic or between cyclic and linear gadolinium compounds. Preincubation of the enzymes with specific inhibitors led to complete inhibition of the respective enzymatic activity. CONCLUSION: The gadolinium-containing and manganese-based magnetic resonance imaging contrast media tested did not exhibit significant inhibition of histamine-inactivating enzymes at physiologically relevant concentrations.

[Suggestions for prevention of adverse reactions after intravasal administration of iodinated contrast media]. / Empfehlungen zur Prophylaxe der Nebenwirkungen bei intravasaler Applikation jodhaltiger Kontrastmittel. Suggestions for prevention of adverse reactions after intravasal administration of iodinated contrast media.

Iodinated contrast media are widely used in computed tomography and angiography. Adverse reactions such as contrast-medium induced nephropathy (CIN), anaphylactoid reactions and iodine-induced thyrotoxicosis are associated with intravasal administration of contrast agents. Iodinated contrast agents are generally considered to be safe, but in rare cases they can cause severe life threatening situations. In this review we present an overview about the incidence, pathways, and risk factors of adverse reactions. Simple schemes including hydration protocols for prevention of CIN, medication for prophylaxis of iodine-induced thyrotoxicosis with thyreostatics and anaphylactoid reactions with histamine antagonists and corticosteroids are suggested.