Risk of cancer incidence before the age of 15 years after exposure to ionising radiation from computed tomography: results from a German cohort study.

The aim of this cohort study was to assess the risk of developing cancer, specifically leukaemia, tumours of the central nervous system and lymphoma, before the age of 15 years in children previously exposed to computed tomography (CT) in Germany. Data for children with at least one CT between 1980 and 2010 were abstracted from 20 hospitals. Cancer cases occurring between 1980 and 2010 were identified by stochastic linkage with the German Childhood Cancer Registry (GCCR). For all cases and a sample of non-cases, radiology reports were reviewed to assess the underlying medical conditions at time of the CT. Cases were only included if diagnosis occurred at least 2 years after the first CT and no signs of cancer were recorded in the radiology reports. Standardised incidence ratios (SIR) using incidence rates from the general population were estimated. The cohort included information on 71,073 CT examinations in 44,584 children contributing 161,407 person-years at risk with 46 cases initially identified through linkage with the GCCR. Seven cases had to be excluded due to signs possibly suggestive of cancer at the time of first CT. Overall, more cancer cases were observed (O) than expected (E), but this was mainly driven by unexpected and possibly biased results for lymphomas. For leukaemia, the SIR (SIR = O/E) was 1.72 (95 % CI 0.89-3.01, O = 12), and for CNS tumours, the SIR was 1.35 (95 % CI 0.54-2.78, O = 7). Despite careful examination of the medical information, confounding by indication or reverse causation cannot be ruled out completely and may explain parts of the excess. Furthermore, the CT exposure may have been underestimated as only data from the participating clinics were available. This should be taken into account when interpreting risk estimates.

Intracranial pressure measurement in infants presenting with progressive macrocephaly and enlarged subarachnoid spaces.

INTRODUCTION: For subarachnomegaly in infants with enlarged external and internal CSF spaces clear treatment decisions, such as observation or ventriculo-peritoneal (VP) shunting, are still lacking. The aim of this study is to measure intracranial pressure (ICP) in these patients to elucidate treatment necessity. MATERIALS AND METHODS: Seven children presenting with macrocephaly, moderately enlarged ventricles, and subarachnoid spaces on magnetic resonance imaging (MRI) without neurological deficits or other CSF-associated pathological conditions were enrolled. Continuous ICP recording was conducted using an external ventricular drain. Data recordings during overnight measurements were analyzed offline to calculate baseline, mean ICP values, and a histogram distribution. RESULTS: Mean age at enrollment was 9.4 months (2-22 months). ICP monitoring was conducted for 2.7 ± 1.1 nights (range 2-5 nights) and revealed baseline values above 10 mmHg in three patients, who went on to receive a VP shunt. One patient with average values over 10 mmHg also underwent VP shunting. Three patients displayed both baseline and average ICP values of less than 10 mmHg. Observational management was chosen for this subgroup. Comparing shunted versus the non-shunted group in a histogram analysis the percentages of recorded ICP values above 8, 10, and 15 mmHg were significantly different (p < 0.05). CONCLUSION: Subarachnomegaly in infants remains a dilemma to the treating neurosurgeon. Risks and benefits of observational management options need to be weighed against those of VP shunting. Continuous ICP monitoring may help to identify patients who may potentially benefit from the surgical treatment option.

[Determination of ventricular volumes in coronary artery disease: comparison of two gated SPECT analysis tools with MRI]. / Bestimmung ventrikulärer Volumina bei koronarer Herzerkrankung: Vergleich zweier Gated-SPECT-Analyseverfahren mit MRT.

AIM: Comparison of two gated SPECT analysis tools -- gated SPECT quantification (GSQ) and emory cardiac toolbox (ECT) -- in patients with coronary artery disease (CAD) and severely impaired left ventricular function (preoperative: EF <35% by cardiac catheter). PATIENTS, METHODS: A total of 56 gated SPECT examinations (one-day hybrid-protocol with (201)Tl-chloride for rest and (99m)Tc-sestamibi for stress applied during low-dose dobutamine stress MR-examination; temporal resolution; 8 phases per cardiac cycle) were performed in 36 patients (31 preoperatively, 25 postoperatively) and compared with MRI in 48 cases. Left ventricular end-diastolic (LV-EDV) and end-systolic (LV-ESV) volumes as well as the left ventricular ejection fraction (LV-EF) were calculated. RESULTS: The total volumetric assessment by both analysis algorithms (n = 56) showed good intraclass correlation coefficients preoperatively (n = 31), but even better postoperatively (n = 25). The mean reconstruction time was approximately 3 minutes ( +/- 2 SD) for GSQ and 15 minutes ( +/- 5 SD) for ECT. In comparison to MRI the results of both analysis tools also correlated well, but the agreement decreased in the presence of scared tissue. The mean LV-EF (MRI) preoperatively was 30.4%, in 6/36 patients above the values calculated from cardiac catheter, postoperatively 34.6%. CONCLUSION: Both gated SPECT analysis tools showed reliable volumetric assessments in high-risk patients with CAD and severely reduced LV-EF in comparison to MRI, with advantages for GSQ in terms of postprocessing time. However, for the calculation of LV-EF a markedly lower concordance with MR-results was observed for both methods depending on the presence of myocardial scars.

[Comparison of different MRI sequences with and without application of Gd-BOPTA as follow-up after LITT]. / Vergleich unterschiedlicher MRT-Sequenzen mit und ohne Applikation von Gd-BOPTA zur Verlaufskontrolle nach LITT.

PURPOSE: Comparison of various MR imaging techniques without and with the application of Gd-BOPTA for the follow-up of thermal tumor ablations by means of laser-induced therapy (LITT). MATERIALS AND METHODS: Thermal tumor ablations were performed with LITT in 19 patients showing a local recurrence. The metastases were from colorectal carcinoma in 15 cases (78.9 %) and from cervix, bronchial, gastric and renal carcinoma respectively in one patient each. The size of the metastases before ablation was on average 38.5 mm (min = 25 mm, max = 58 mm). The MRI protocol consisted of T2 UTSE FS, T1 w GRE without and with Gd-BOPTA at an early (20 s post injection) and late stage (> 120 min post injection). Two independent radiologists evaluated image contrast of the local relapse and necrosis in comparison to the surrounding healthy liver parenchyma on a scale from - 10 to + 10. Liver parenchyma was in any sequence 0. Recurrences were confirmed with follow-up examinations in all patients. Statistical analysis was performed by means of Wilcoxon and Kendall's W-test. RESULTS: Both radiologists found absolute ratios for contrast differences between thermal necrosis and local recurrence, with an average of 10.95 for T2 w UTSE FS and of 6.58 for T1 w GRE without, and of 4.05 for T1 w GRE with Gd-BOPTA in the early and of 2.26 in the late stage. Superiority for UTSE FS was significant (p < 0.05). The statistical analysis showed a high agreement for both radiologists for all values (p < 0.001). CONCLUSION: For early detection of local recurrences after thermal ablation T2 w UTSE FS is most suitable. For the detection of new foci, the use of liver specific contrast media is advisable.

Comparison of different cardiac MRI sequences at 1.5 T/3.0 T with respect to signal-to-noise and contrast-to-noise ratios - initial experience.

PURPOSE: To compare image quality, signal-to-noise (SNR) and contrast-to-noise ratios (CNR) of different MRI sequences for cardiac imaging at 1.5 T and 3.0 T in volunteers. MATERIAL AND METHODS: 10 volunteers (5 male, 5 female) with a mean age of 33 years (+/- 8) without any history of cardiac diseases were examined on a GE Signa 3.0 T and a GE Signa 1.5 T TwinSpeed Excite (GE Medical Systems, Milwaukee, WI, USA) scanner using a 4-element phased array surface coil (same design) on the same day. For tissue characterization ECG gated Fast Spinecho (FSE) T (1)- (Double IR), T (1)-STIR (Triple IR) and T (2)-weighted sequences in transverse orientation were used. For functional analysis a steady state free precession (SSFP - FIESTA) sequence was performed in the 4-chamber, 2-chamber long axis and short axis view. The flip angle used for the SSFP sequence at 3.0 T was reduced from 45 degrees to 30 degrees to keep short TR times while staying within the pre-defined SAR limitations. All other sequence parameters were kept constant. RESULTS: All acquisitions could successfully be completed for the 10 volunteers. The mean SNR 3.0 T compared to 1.5 T was remarkably increased (p < 0.05) for the T (2) - (160 % SNR increase), the STIR-T (1)- (123 %) and the T (1)- (91 %) weighted FSE. Similar results were found comparing CNR at 3.0 T and 1.5 T. The mean SNR achieved using the SSFP sequences was more than doubled by 3.0 T (150 %), but did not have any significant effect on the CNR. The image quality at 3.0 T did not appear to be improved, and was considered to be significantly worse when using SSFP sequences. Artefacts like shading in the area of the right ventricle (RV) were found to be more present at 3.0 T using FSE sequences. After a localized shim had been performed in 5/10 volunteers at the infero-lateral wall of the left ventricle (LV) with the SSFP sequences at 3.0 T no significant increase in artefacts could be detected. CONCLUSIONS: In all cardiac FSE sequences, SNR and CNR at 3.0 T were found to be increased compared to 1.5 T without any major changes of the sequence parameters. The adjusted SSFP sequences fulfilled the expected increase in SNR at 3.0 T but showed no increase in CNR. On the contrary, the overall image quality did not change or was even found to be significantly lower for the SSFP and the FSE sequences at the free wall of the RV. Nevertheless, the results are encouraging for the use of 3.0 T for cardiac tissue characterization and new applications with progressing use of parallel imaging.

Posterior reversible encephalopathy syndrome in children: radiological and clinical findings - a retrospective analysis of a German tertiary care center.

PURPOSE: To report the radiological and clinical spectrum of posterior reversible encephalopathy syndrome (PRES) in children in a German tertiary referral center. METHODS: The radiological report data bases of the authors' university hospitals were searched for paediatric patients with PRES. Clinical and paraclinical data as well as various imaging features at symptom onset and during follow-up were tabulated in patients fulfilling the criteria for PRES. RESULTS: A total of 18 paediatric patients with PRES were included into the study. Mean age was 9 years (IQR 7-12), 38.9% were females. Most frequent predisposing causes were renal and haemato-oncologic diseases frequently associated with endotheliotoxic cytostatic medication. Frontal lesions occurred as frequently as parietal lesions followed by occipital lesions. The superior frontal sulcus topographic lesion pattern occurred as frequent as the parieto-occipital one. In 38% of cases residual lesions were encountered with focal laminar necroses being most frequent. Initial clinical syndromes associated with PRES included seizures in 18, altered mental state in 5, and hemiparesis and visual disturbances in 2 children. Mean arterial blood pressure at onset of PRES was 140/85 mmHg (IQR systolic: 124-169, diastolic: 78-93 mmHg). CONCLUSION: Paediatric PRES in this cohort comprises a broad radiological and clinical spectrum. The occurrence of frontal lesions, a superior frontal sulcus associated lesion pattern, and the development of focal laminar necrosis appear to be frequent in children.

Pulmonary and caval blood flow patterns in patients with intracardiac and extracardiac Fontan: a magnetic resonance study.

AIMS: We compared in vivo blood flow and pulsatility after different types of Fontan operation using magnetic resonance imaging. MATERIAL AND METHODS: A total of 37 consecutive patients (mean age 19+/-7.9 years, 7.3+/-3.2 years after Fontan operation), 7 with atriopulmonary anastomosis (APC), 18 with intra-atrial lateral tunnel (LTFO) and 12 with extracardiac Fontan (ECFO) were studied using magnetic resonance phase-contrast velocity mapping. Blood flow (volume flow) in the superior vena cava (SVC), inferior vena cava (IVC) and both pulmonary arteries were measured and a pulsatility index was calculated for each vessel. RESULTS: For all modifications, the blood flow distribution between the SVC and IVC was normal (1:2). Patients with APC had a normal pulsatility, a dilated right atrium, partial backward flow in the IVC and physiological blood flow distribution between the pulmonary arteries. LTFO and ECFO patients had no retrograde flow in the IVC, equal blood flow distribution between the pulmonary arteries and very low or absent pulsatility. CONCLUSIONS: MRI allows hemodynamic quantification and characterization of various types of Fontan modifications and may be a valuable tool to predict Fontan failure. Despite showing normal pulsatility, patients with APC have right atrial dilatation and partial backward flow in the IVC, demonstrating suboptimal Fontan circulation. LTFO and ECFO both produce unidirectional antegrade flow in the IVC but pulsatility is very low or absent, which may promote poor pulmonary artery growth and increase of pulmonary vascular resistance contributing to late Fontan failure.

Pulmonary regurgitation is a powerful factor influencing QRS duration in patients after surgical repair of tetralogy of Fallot. A magnetic resonance imaging (MRI) study.

AIMS: QRS prolongation is a negative prognostic factor for the development of ventricular arrhythmia after repair of tetralogy of Fallot (TOF). In this MRI study, we performed a multivariate analysis to determine the influence of volumetric and functional parameters as well as time factors on QRS duration. METHODS AND RESULTS: Sixty-seven patients after surgical repair of TOF were studied using a 1.5T MRI. Measurement of the ventricles was performed with a multislice-multiphase sequence. Left and right ventricular volumes, ejection fractions (EF) and myocardial masses were determined. Pulmonary regurgitant fraction (PRF) was quantified by velocity encoded flow measurement in the main pulmonary artery. Maximum QRS duration was taken from a 12-channel ECG. Mean maximum QRS duration was 132 ms (+/- 29 ms). Mean PRF was 29.2% (+/- 13.4%). QRS duration correlated significantly with PRF (r = 0.49; p < 0.01; n = 54) and with right ventricular enddiastolic volume index (RVEDVI) (r = 0.29; p < 0.05; n = 67). Multivariate analysis revealed that the combination of PRF, postoperative period, age at surgical repair, and left ventricular (LV) enddiastolic volume are correlated with QRS prolongation. CONCLUSION: In patients after repair of TOF, pulmonary regurgitation is related to QRS prolongation. Furthermore, even LV size plays a role in the enlargement of the QRS complex.

Restriction of Toxoplasma gondii growth in human brain microvascular endothelial cells by activation of indoleamine 2,3-dioxygenase.

One of the first steps in the development of cerebral toxoplasmosis is the penetration of the blood-brain barrier, which is comprised of microvascular endothelial cells. We examined the capacity of human brain microvascular endothelial cells (HBMEC) to interact with Toxoplasma gondii. We found that stimulation of HBMEC with gamma interferon (IFN-gamma) resulted in the induction of toxoplasmostasis. The capacity of HBMEC to restrict Toxoplasma growth after IFN-gamma stimulation was enhanced in the presence of tumor necrosis factor alpha (TNF-alpha). In addition, we found that IFN-gamma induced a strong induction of indoleamine 2,3-dioxygenase (IDO) activity in HBMEC, and this enzyme activity was enhanced by costimulation with TNF-alpha. The addition of excess amounts of tryptophan to the HBMEC cultures resulted in a complete abrogation of the IFN-gamma-TNF-alpha-mediated toxoplasmostasis. We therefore conclude that IDO induction contributed to the antiparasitic effector mechanism inducible in HBMEC by IFN-gamma and TNF-alpha.

Potential role of human brain microvascular endothelial cells in the pathogenesis of brain abscess: inhibition of Staphylococcus aureus by activation of indoleamine 2,3-dioxygenase.

Cerebral abscess is a rare complication of staphylococcal septicemia in infants associated with high mortality and morbidity. In the pathogenesis of abscess formation, S. aureus, one major causative agent, interacts with endothelial cells of the brain vessels before reaching the central nervous system. This study examined the growth of S. aureus in human brain microvascular endothelial cells (HBMEC) cultures stimulated with cytokines. IFN-gamma inhibited S. aureus replication by the induction of indoleamine 2,3-dioxygenase (IDO) in HBMEC. This activation of IDO in HBMEC could be shown by RT-PCR and by detection of kynurenine in culture supernatants of activated cells. Resupplementation of L-tryptophan abrogated the inhibitory effect of IFN-gamma on the growth of staphylococci, hence confirming the activation of indoleamine 2,3-dioxygenase as being responsible for the induced bacteriostasis. Addition of TNF-alpha enhanced the IFN-gamma mediated antibacterial effects, whereas TNF-alpha alone had no influence on staphylococcal growth. Stimulation of HBMEC with IFN-gamma failed to activate inducible nitric oxide synthase (iNOS) and subsequent production of nitric oxide (NO). Thus, intra- and extracellular depletion of L-tryptophan seems to be an important process in the defense against staphylococcal brain abscesses by means of creating an unfavorable microenvironment.

[The use of cross-sectional imaging modalities in the diagnosis of heart valve diseases]. / Einsatz moderner Schnittbildverfahren in der Diagnostik von Herzklappenerkrankungen.

Exact visualization of valve morphology seems to be possible with the cross-sectional imaging modalities, magnetic resonance imaging (MRI) and the recently introduced technique of multi-detector computed tomography (MDCT). These techniques are used, if other non-invasive imaging modalities, like echocardiography, fail or provide only insufficient information. This commonly occurs in the assessment of right ventricular valves. Quantification of valve stenosis is possible by calculating valve orifice area, which can be performed with MRI and MDCT. An estimation of the instantaneous peak gradient can only be achieved by MR flow measurements. MR flow measurement is a reliable method to quantify the degree of mild to moderate stenoses. Quantification of valve regurgitation is possible by measurement of the regurgitation fraction with MR flow measurements as well as with MR volumetry/CT volumetry. But only the MR flow measurement is suitable for the quantification of valve regurgitation in patients with multiple valves involved or cardiac shunting. MRI and probably MDCT are the most reliable methods in the evaluation of ventricular volumes and therefore suitable for the follow-up in patients with valvular heart disease, because changes in volumes are important for therapeutic decisions in these patients. The crucial advantages of MRI compared to CT in the diagnostic of valvular heart diseases however are the absence of radiation exposure, the possibility of quantitative evaluation of valves function using flow measurements and the higher temporal resolution as compared to MDCT.

[The use of cross-sectional imaging modalities in the diagnosis of valvular heart disease]. / Einsatz moderner Schnittbildverfahren in der Diagnostik von Herzklappenerkrankungen.

Exact visualization of valve morphology seems to be possible with the cross-sectional imaging modalities, magnetic resonance imaging (MRI) and the recently introduced technique of multidetector computed tomography (MDCT). These techniques are used, if other non-invasive imaging modalities, like echocardiography, fail or provide only insufficient information. This commonly occurs in the assessment of right ventricular valves. Quantification of valve stenosis is possible by calculating valve orifice area, which can be performed with MRI and MDCT. An estimation of the instantaneous peak gradient can only be achieved by MR flow measurements. MR flow measurement is a reliable method to quantify the degree of mild to moderate stenoses. Quantification of valve regurgitation is possible by measurement of the regurgitation fraction with MR flow measurements as well as with MR volumetry/CT volumetry. But only the MR flow measurement is suitable for the quantification of valve regurgitation in patients with multiple valves involved or cardiac shunting. MRI and probably MDCT are the most reliable methods in the evaluation of ventricular volumes and therefore suitable for the follow-up in patients with valvular heart disease, because changes in volumes are important for therapeutic decisions in these patients. The crucial advantages of MRI compared to CT in the diagnostic of valvular heart diseases however are the absence of radiation exposure, the possibility of quantitative evaluation of valves function using flow measurements and the higher temporal resolution as compared to MDCT.