[Evaluation of a novel seldinger-needle for computed tomography guided interventions: initial experiences]. / Evaluierung einer neuen Seldinger-Nadel für computertomografisch gesteuerte Interventionen: Erste Erfahrungen.

PURPOSE: To evaluate a new Seldinger puncture device for computed tomography-guided interventions under difficult conditions, to analyze applicability, and to investigate assets and drawbacks. MATERIALS AND METHODS: From November 2007 to March 2008, we performed CT-guided interventions in 16 patients (7 women, 9 men; mean age 62 years old) using a new 20G-Seldinger needle (Sika-Med, Wiehl, Germany). This novel needle serves as a guide for many different interventional devices due to a guide wire welded on the proximal needle end. It allows continuous application of anesthesia via four tiny holes at the distal needle end until the region of interest is reached. Each intervention was subject to difficult interventional conditions. The indications for intervention were drainage (n = 7), Trucut biopsy of tumor (n = 8) and radiofrequency ablation (n = 1). Handling, success, advantages, drawbacks, complications and patient tolerance were noted after each procedure. A pain scale from 1 - 10 was used to grade the pain level during the intervention. RESULTS: All interventions were performed successfully and no severe complications were observed. Patient tolerance was very good resulting in a mean pain score of 2 +/- 1. Regions with dangerous and difficult access were successfully reached with the new Seldinger needle in 15 of 16 cases by dilatation of the puncture tract and continuous administration of local anesthesia via the system. Furthermore, different devices such as Trucut systems and a drainage catheter were able to be inserted without complication via the needle. With a proximal removable luer-lock connection, liquid material was able to be aspirated in six cases. CONCLUSION: Under difficult interventional conditions, the use of a Seldinger needle as a reliable technique for CT-guided interventions can provide a safe and successful procedure.

[Human Bocavirus-infection (HBoV): an important cause of severe viral obstructive bronchitis in children]. / Infektionen mit dem humanen Bocavirus (hBoV): Eine wichtige Ursache schwerer viraler Atemwegsinfektionen im frühen Kindesalter.

BACKGROUND: Apart from established pathogens of lower respiratory tract infections, such as respiratory syncytial virus (RSV), an increasing number of additional agents has been identified in recent years. In 2005 the human bocavirus (hBoV) has been isolated from respiratory tract samples and has been reported worldwide with frequencies ranging from 1.5 to 18.3% in respiratory samples from children with airway infections. PATIENTS: We investigated 173 specimens of a total number of 162 children who were inpatients with severe respiratory tract infections most of whom required oxygen therapy. METHOD: We analyzed respiratory tract samples (83% nasopharyngeal washes, 15% tracheal secretions, 2% bronchoalveolar lavages) for adenoviruses, influenza A und B viruses, parainfluenzaviruses types 1 to 3 and RSV using antigen-specific immunofluorescence assays. Additionally we tested human metapneumovirus (hMPV) and hBoV using a PCR assay. MAIN RESULTS: 35.8% specimens were negative in all assays, 54.3% were positive for RSV and 9.8% were positive for adeno-, influenza-, parainfluenzaviruses or hMPV. HBoV could be detected in 17 specimens (9.8%), defining HBoV to be the second most frequent pathogen. Nine of these patients showed a coinfection with RSV, one with parainfluenza virus. Viral loads did range from 2x10 (2) to 5.6x10 (10) genome equivalents/ml with higher viral loads being observed in the first days after disease onset. Most children were infected in the months between December and April. Half of the patients with isolated HBoV infection showed rhinopharyngitis, a third suffered from pulmonary obstruction and nearly every second required oxygen therapy. However, no HBoV-specific symptoms were found. CONCLUSION: HBoV is a common pathogen causing viral respiratory tract infection in infants and young children. Among the here reported patients HBoV was the second most frequent identified pathogen. X-ray studies frequently revealed peribronchial and pneumonic infiltrates with only moderately elevated laboratory inflammatory markers. So far, no HBoV-specific clinical symptoms are known. Additional questions for example related to the way of transmission and optimal treatment remain to be investigated in prospective studies.

[Computer-aided detection of small pulmonary nodules in multidetector spiral computed tomography (MSCT) in children]. / Computerassistierte Detektion (CAD) von kleinen pulmonalen Rundherden in der Mehrdetektor-Spiral-Computertomografie (MDCT) bei Kindern.

PURPOSE: Retrospective evaluation of computer-aided detection software (CAD) for automated detection (LungCAD, Siemens Medical solutions, Forchheim, Germany) and volumetry (LungCARE) of pulmonary nodules in dose-reduced pediatric MDCT. MATERIALS AND METHODS: 30 scans of 24 children (10.4+/-5.9 years, 13 girls, 11 boys, 39.7+/-29.3 kg body weight) were performed on a 16-MDCT for tumor staging (n=18), inflammation (n=9), other indications (n=3). Tube voltage 120 kVp and effective mAs were adapted to body weight. Slice thickness 2 mm, increment 1 mm. A pediatric radiologist (U1), a CAD expert (U2) and an inexperienced radiologist (U3) independently analyzed the lung window images without and with the CAD as a second reader. In a consensus decision U 1 and U 2 were the reference standard. RESULTS: Five examinations had to be excluded from the study due to other underlying lung disease. A total of 24 pulmonary nodules were found in all data sets with a minimal diameter of 0.35 mm to 3.81 mm (mean 1.7+/-0.85 mm). The sensitivities were as follows: U1 95.8% and 100% with CAD; U2 91.7% U3 66.7%. U2 and U3 did not detect further nodules with CAD. The sensitivity of CAD alone was 41.7 % with 0.32 false-positive findings per examination. Interobserver agreement between U1 / U2 regarding nodule detection with CAD was good (k=0.6500) and without CAD very good (k=0.8727). For the rest (U1 /U3; U2 / U3 with and without CAD), it was weak (k=0.0667-0.1884). Depending on the measured value (axial measurement, volume), there is a significant correlation (p=0.0026-0.0432) between nodule size and CAD detection. Undetected pulmonary nodules (mean 1.35 mm; range 0.35-2.61 mm) were smaller than the detected ones (mean 2.19 mm; range 1.35-3.81 mm). No significant correlation was found between CAD findings and patient age (p=0.9263) and body weight (p=0.9271) as well as nodule location (subpleural, intraparenchymal; p=1.0) and noise/SNR. CONCLUSION: In our study with 2 mm slice thickness and very small lesion sizes, the analyzed CAD algorithm for detection and volumetry of pulmonary nodules has limited application in pediatric dose-reduced 16-MDCTs. Determination of lesion size is possible even in the case of false-negatives.

[Pediatric bowel MRI--accelerated parallel imaging in a single breathhold]. / MRT des darms bei kindern--beschleunigte bildgebung in einem atemzug.

PURPOSE: To compare highly accelerated parallel MRI of the bowel with conventional balanced FFE sequences in children with inflammatory bowel disease (IBD). MATERIALS AND METHODS: 20 children with suspected or proven IBD underwent MRI using a 1.5 T scanner after oral administration of 700 -1000 ml of a Mannitol solution and an additional enema. The examination started with a 4-channel receiver coil and a conventional balanced FFE sequence in axial (2.5 s/slice) and coronal (4.7 s/slice) planes. Afterwards highly accelerated (R = 5) balanced FFE sequences in axial (0.5 s/slice) and coronal (0.9 s/slice) were performed using a 32-channel receiver coil and parallel imaging (SENSE). Both receiver coils achieved a resolution of 0.88 x 0.88 mm with a slice thickness of 5 mm (coronal) and 6 mm (axial) respectively. Using the conventional imaging technique, 4 - 8 breathholds were needed to cover the whole abdomen, while parallel imaging shortened the acquisition time down to a single breathhold. Two blinded radiologists did a consensus reading of the images regarding pathological findings, image quality, susceptibility to artifacts and bowel distension. The results for both coil systems were compared using the kappa-(kappa)-coefficient, differences in the susceptibility to artifacts were checked with the Wilcoxon signed rank test. Statistical significance was assumed for p = 0.05. RESULTS: 13 of the 20 children had inflammatory bowel wall changes at the time of the examination, which could be correctly diagnosed with both coil systems in 12 of 13 cases (92 %). The comparison of both coil systems showed a good agreement for pathological findings (kappa = 0.74 - 1.0) and the image quality. Using parallel imaging significantly more artifacts could be observed (kappa = 0.47) without impairing the diagnostic impact. The comparison of the bowel distension showed no significant differences. CONCLUSION: The highly accelerated parallel MRI using the SENSE technique and a 32-channel surface coil enables the examination of the entire bowel in a single breathhold without relevant restrictions in image quality and diagnostic impact.

Pediatric multidetector computed tomography using tube current modulation and a patient image gallery.

BACKGROUND: Dose reduction is crucial in pediatric multidetector computed tomography (MDCT). PURPOSE: To perform pediatric 16-slice MDCT using tube current modulations and to adjust prospectively the tube current using a patient image gallery (IG) providing simulated dose-reduced protocols; and to evaluate and compare the image quality of the IG and the clinical MDCT. MATERIAL AND METHODS: 30 examinations (thorax, n = 15; abdomen, n = 8; pelvis, n = 7) in 20 patients (nine male, age 8.05 +/- 7.33 years, weight 29.8 +/- 24.02 kg) were performed according to an IG on a 16-slice MDCT with additional use of online tube current modulation (CARE Dose). Three radiologists visually assessed image quality from the IG and actual 16-slice MDCT scans. For objective analysis, image noise was determined. RESULTS: Statistical analysis showed moderate concordance in objective (K = 0.68-0.78) and subjective (K = 0.33-0.64) image assessment between the IG and clinical 16-slice MDCT scans. Depending on the weight group and clinical question, no or only minor dose reductions in the chest, but moderate to considerable reductions in the abdominal/pelvic 16-slice MDCT scans compared to previously used pediatric protocols were achieved. Extra dose reduction was achieved due to additional use of CARE Dose depending on age group and scan region (mean 8.6-23.9%). CONCLUSION: The IG enabled us to prospectively reduce the tube current and adapt the required image quality to the clinical question. Additional dose reduction was achieved with application of CARE Dose; nevertheless, the images are comparable to the simulated images of the IG.

[CT-guided interventions in children]. / Computertomografisch gesteuerte Interventionen bei Kindern.

In pediatric CT-guided interventions specific features have to be taken into account. Due to a lack of cooperation or limited ability to cooperate, procedures are often performed using analgosedation or general anesthesia. To provide radiation protection, justified indication for CT-guided intervention is necessary and sonography and MRI are to be preferred whenever possible. CT examinations also need to be dose-adapted with sequential scanning and a tube voltage and tube current reduction compared to pediatric diagnostic CT studies must be ensured. Gonad shields are recommended for male patients. Biopsy device selection depends on the assumed tumor entity since histology and also immunohistochemical, molecular pathological and cytogenetical analysis are necessary to differentiate pediatric tumors (small, round, blue cell tumors). In addition to diagnostic procedures, therapeutic interventions (drainage, injection therapies, neurolysis, and radiofrequency ablation) can also be used in children and can provide an alternative to surgery in selected cases. With justified indications and precise performance, CT-guided interventions can be successful in pediatric patients with limited risks.

Ultrasonography of the pancreas. 2. Harmonic imaging.

Tissue harmonic imaging (THI) is a relatively new ultrasonographic imaging modality which has been implemented in many modern scanners. As several previous studies have pointed out, THI can help to overcome some shortcomings of conventional B-mode ultrasonography (US). The aim of this article is to give a compact summary of the potentials of THI, focused on pancreatic imaging. Beginning with a recapitulation of the technical background of THI, the particularities and suitable applications of THI in US of the pancreas are discussed. Examination protocols and typical indications are presented together with example images. Finally, new trends and developments in B-mode sonography of the pancreas such as panorama US, compound imaging, and photopic US are mentioned.

Evaluation of femoral head vascularization in slipped capital femoral epiphysis before and after cannulated screw fixation with use of contrast-enhanced MRI: initial results.

In this study we used contrast-enhanced magnetic resonance imaging (MRI) to evaluate the vascularization of the femoral head in children with slipped capital femoral epiphysis (SCFE) before and after cannulated screw fixation. Eleven consecutive children with SCFE, seven boys and four girls, aged 10-15 years were included in the study. There were no preslips; four children had acute, three acute-on-chronic, and four chronic SCFE. The MRI examinations were performed in a 1.5 Tesla MR scanner with use of a coronal STIR sequence, a coronal contrast-enhanced T1-weighted spin-echo sequence, and a sagittal three-dimensional gradient-echo sequence. Morphology, signal intensities, and contrast-enhancement of the femoral head were assessed by two radiologists in consensus. Morphologic distortion of the physis, bone marrow edema within the metaphysis and epiphysis, and joint effusion were the preoperative MRI findings of SCFE in each child. In nine children, the vascularization of the femoral head before and after surgery was normal. In one child, a preoperative avascular zone in the superolateral aspect of the epiphysis revascularized completely after surgery. One child with severe SCFE developed avascular necrosis of the femoral head after open reduction of the slip. We conclude that MRI allows for accurate evaluation of the femoral head vascularization before and after surgery in children with SCFE.

Radiation dose reduction to breast and thyroid during MDCT: effectiveness of an in-plane bismuth shield.

PURPOSE: To evaluate dose reduction and image deterioration using in-plane bismuth breast-shielding and thyroid-shielding for MDCT. MATERIAL AND METHODS: Skin and organ doses of thyroid and breast were measured with thermoluminescent dosimeters in a female Alderson-Rando Phantom with and without a 4-ply in-plane bismuth shield. Routine neck (120 kVp, 150 mAs(eff); 16 x 1.5 mm) and chest (120 kVp, 100 mAs(eff); 16 x 1.5 mm) scan protocols were simulated on a 16-row MDCT scanner in three different settings: without shielding, with the shield directly on the surface, and with a 1-cm-thick cotton spacer between surface and shield. Image noise was quantified and compared using the t test. RESULTS: On average, shielding resulted in a 47% organ-dose reduction for the thyroid and 32% for the breast. Placement of the spacer between shield and surface had no significant impact on the measured doses, but significantly decreased the image noise (P < 0.05). CONCLUSION: In-plane bismuth breast and thyroid shielding significantly decreases radiation dose in MDCT without deteriorating image quality.

[Dose-reduced 16-slice multidetector-row spiral computed tomography in children with bronchoscopically suspected vascular tracheal stenosis -- initial results]. / Dosisreduzierte 16-Schicht-Multidetektor-Spiralcomputertomographie bei Säuglingen und Kleinkindern mit bronchoskopischem Verdacht auf vaskulär bedingte Trachealstenosen -- erste klinische Ergebnisse.

PURPOSE: To evaluate the diagnostic accuracy of contrast-enhanced dose-reduced 16-slice multidetector-row CT (MDCT) in newborns and infants with fiberoptic bronchoscopically suspected vascular-induced tracheal stenosis. MATERIALS AND METHODS: 12 children (4 days to 3 years, 1.2 - 13.5 kg body weight) were examined using i. v. contrast-enhanced 16-slice MDCT (SOMATOM Sensation 16, Forchheim, Germany) without breath-hold and under sedation (11/12). All MDCTs were performed with a dose reduction. The beam collimation was 16 x 0.75 mm, except in the case of one child. MPRs along the tracheal axis in the x-, y- and z-directions and volume-rendering-reconstructions (VRTs) were calculated based on a secondary raw data set in addition to conventional axial slices. 2 radiologists used a three-point grade scale to evaluate the image quality, motion, and contrast media artifacts as well as the usefulness of the 2D- and 3D-reconstructions for determining the diagnosis. Statistical analysis was performed on the basis of a Kappa test. RESULTS: In all cases the cause of the fiberoptic bronchoscopically suspected tracheal stenosis was revealed: compression due to the brachiocephalic trunk (n = 7), double aortic arch (n = 2), lusorian artery (n = 1), vascular compression of the left main bronchus (n = 2). In 3 patients further thoracic anomalies, such as tracheobronchial (n = 2), and vascular (n = 2) and vertebral (n = 1) anomalies were found. The attenuation in the anomalous vessels was 307 +/- 140 HU. The image noise was 9.8 +/- 1.9 HU. The mean dose reduction was 82.7 +/- 3.2 % compared to a standard adult thoracic CT. All examinations were rated as diagnostically good (median 1, range 1, k = 1). 3D images did not show any stair artifacts (median 2, range 1 - 2, k = 1). The image noise was minor to moderate and hardly any motion artifacts were seen (median 1, range 1 - 2, k = 0.8). Contrast media artifacts were rated zero to minor (median 1.5, range 1 - 2, k = 0.676). MPRs (median 1, range 1, k = 1) and VRTs (median 1, range 1, k = 1) were found to be useful for diagnosis. Subsequent vascular surgery was performed on 8 patients. CONCLUSION: Contrast-enhanced dose-reduced 16-slice MDCT is effective for demonstrating the cause of fiberoptic bronchoscopically suspected vascular-induced tracheal stenosis even in very small and severely ill children despite the small contrast media amount and free breathing.

Phase-inversion tissue harmonic imaging compared to fundamental B-mode ultrasound in the evaluation of the pathology of large and small bowel.

Our purpose was to compare phase-inversion harmonic imaging (PIHI) with conventional B-mode ultrasound (US) regarding image quality in the evaluation of bowel pathology. Forty-one patients prospectively underwent intestinal ultrasound scans with US and PIHI in randomly chosen order. Crucial technical parameters were standardized. Bowel morphology as well as perienteric pathology and complications were documented. In 24 cases, the ultrasound results were compared to those of other imaging modalities. Three radiologists evaluated (1) overall image quality, (2) lesion conspicuity and diagnostic confidence, and (3) detection of free fluid on hardcopy films. The ratings for image quality were compared using the two-sample paired t test for means and Bowker's test for symmetry (p=0.05). Compared to US, PIHI provided significantly better overall image quality, lesion conspicuity and diagnostic confidence, as well as better detection of free fluid (p< 0.05). Bowel wall pathology, detected by both modalities, showed good correlation to additional imaging modalities. In 12 patients (29.3%), a gain of crucial diagnostic information was observed with PIHI when compared to US. PIHI significantly enhances sonography of the intestine by offering better overall image quality, better visualization of bowel pathology and associated changes. Additionally, PIHI adds crucial diagnostic information in several patients.

[Multislice spiral CT (MSCT) in pediatric radiology: dose reduction for chest and abdomen examinations]. / Mehrschicht-Spiral-CT (MSCT) in der Kinderradiologie: Dosisreduktion bei der Untersuchung von Thorax und Abdomen.

The advent of multislice spiral CT (MSCT) technique has led to new aspects of dose reduction, especially for the dedicated use of MSCT in children. Optimizing pediatric MSCT protocols according to the clinical problem allows reduction of radiation exposure to a minimum without loss of diagnostic quality. The different parameters that influence the degree of dose reduction, like tube current-time product (mAs), tube voltage (kV), collimation and pitch, are discussed in context with previously published data and our own experience in nearly 200 pediatric CT examinations. In our department, the effective mAs is calculated for a pediatric chest MSCT by multiplication of the body weight in kilogram with a factor of 1 to 1.5 and for a pediatric abdominal MSCT by multiplication with a factor of 2 to 2.5. To calculate the equivalent effective dose for a contrast media-enhanced 80 kV protocol, the effective mAs of the 120 kV protocol can be multiplied by 2.7. A factor less than 2.7 means further dose reduction. Compared to the radiation exposure with a standard adult protocol, the effective dose in a pediatric thoracic MSCT could be reduced by up to 92 % in neonates, 89 % in toddlers and 80 % in school children. In abdominal MSCT, the effective dose could be reduced by up to 90 % in neonates, 89 % in toddlers and 83 % in school children. Using an adequate MSCT technique in children by adjusting the CT scanning parameters to the clinical question and body weight of the examined child enables a significant reduction of radiation exposure in comparison to standard MSCT protocols.