Torso shape detection to improve lung monitoring.

OBJECTIVE: Newborns with lung immaturity often require continuous monitoring and treatment of their lung ventilation in intensive care units, especially if born preterm. Recent studies indicate that electrical impedance tomography (EIT) is feasible in newborn infants and children, and can quantitatively identify changes in regional lung aeration and ventilation following alterations to respiratory conditions. Information on the patient-specific shape of the torso and its role in minimizing the artefacts in the reconstructed images can improve the accuracy of the clinical parameters obtained from EIT. Currently, only idealized models or those segmented from CT scans are usually adopted. APPROACH: This study presents and compares two methodologies that can detect the patient-specific torso shape by means of wearable devices based on (1) previously reported bend sensor technology, and (2) a novel approach based on the use of accelerometers. MAIN RESULTS: The reconstruction of different phantoms, taking into account anatomical asymmetries and different sizes, are produced for comparison. SIGNIFICANCE: As a result, the accelerometers are more versatile than bend sensors, which cannot be used on bigger cross-sections. The computational study estimates the optimal number of accelerometers required in order to generate an image reconstruction comparable to the use of a CT scan as the forward model. Furthermore, since the patient position is crucial to monitoring lung ventilation, the orientation of the phantoms is automatically detected by the accelerometer-based method.

Primary renal neuroblastoma metastasizing into liver and lungs with tumor thrombus extension into the right atrium.

Neuroblastomas are malignant tumors of the sympathetic nervous system. Areas of manifestation most commonly involve the abdomen, neck, thorax and pelvis. Primary renal neuroblastomas are extremely rare, only a few case reports exist worldwide, and even those are discussed controversially.We present the case of a 6-year-old girl with a renal tumor and a tumor thrombus extending into the right atrium, which radiologically appeared to be a Wilms tumor. Since the lesion did not respond to nephroblastoma-specific therapy, a biopsy from one of the liver metastases was taken, revealing the revised diagnosis of a clear cell renal cell carcinoma. Histopathology of the reference center, however, described a primary renal neuroblastoma. After adjusting the chemotherapy tumornephrectomy including the complete venous thrombus could be performed without any complications.Neuroblastoma originating from a kidney is an absolute rarity that can easily be misdiagnosed as Wilms tumor, especially, if a typical tumor thrombus with extension into the inferior vena cava is seen. Therefore neuronspecific enolase in serum as well as vanillylmandelic acid and homovanillic acid in the urine should be determined in all patients when Wilms tumor is assumed. To the best of our knowledge, this is the first published case of a primary renal neuroblastoma with a tumor thrombus extending into the right atrium.

[Clinical relevance and indications for cardiac magnetic resonance imaging 2013: an interdisciplinary expert statement]. / Klinischer Stellenwert und Indikationen zur Magnetresonanztomografie des Herzens 2013: Ein interdisziplinäres Expertenstatement.

During the last years the indications of Cardiac Magnetic Resonance Imaging (CMRI) have been continuously expanded. However, the acceptance of the method by cardiologists and radiologists does not correlate with respect to the diagnostic potential. Several factors, such as expensive equipment, relatively long examination times, high technical know how and lack of remuneration, limit the application of CMRI in everyday clinical practice. Furthermore, doctors tend to apply more conventional, well established diagnostic procedures, the access to the method is still limited and there exist difficulties in the interdisciplinary collaboration. The interdisciplinary Austrian approach to Cardiac Imaging is aimed to improve the aforementioned problems and to support the implementation of CMRI in the diagnostic tree of cardiac diseases thus enabling a cost efficient management of patients in cardiology.

CT in children--dose protection and general considerations when planning a CT in a child.

Today CT represents about 10% of all ionizing radiation based imaging modalities, but delivers more than 50% of the total collective dose for diagnostic imaging. Compared to adults the radiation sensitivity of children is considerable higher than in adults. Additionally children differ from adults--factors like body size, mass, density, proportions as well as metabolism have to be mentioned. Children grow and mature--all this components have to be mapped in examination protocols by Pediatric Radiology. The total dose of a CT examination depends on the settings of several factors such as the scout view, the scan length, exposure settings including automated exposure control, type of scanning (single slice, helical, volume mode), slice thickness, pitch values as well as on image reconstruction parameters. If intravenous contrast media injection is needed bolus tracking or timing represents another source of radiation. The aim of the paper is to present and discuss all aspects of defining a pediatric age and query adapted CT protocol particularly concerning all dose relevant factors in pediatric CT and their adjustment in children. Moreover hints are given concerning optimization of intravenous contrast media injection as well as special (low dose) imaging protocols.

Experience with volumetric (320 rows) pediatric CT.

The introduction of helical computer tomography (CT) and further progress to multi-slice CT enabled new applications. Most recent developments like the 320-row detector facilitate volume CT, which avoids the over-beaming effect of helical scanning. The 320-row multi-slice detector CT (MDCT) is based on a 16cm detector; a special acquisition mode allows reconstructing 640 slices from these 16cm. The shortest tube rotation time is in cardiac mode 0.35s, otherwise 0.4s and 0.5s used. At 0.5s the machine already reaches the maximum numbers of sub-second projections. Scan modes can be volume, helical and single slice mode. For image acquisition all dose savings technologies like variable tube position for scano-view, active collimation, automated exposure control, bolus and ECG tracking are available. Additionally special acquisition and post-processing techniques like head and body perfusion CT are ready for use on the console. For image reconstruction properties like filtered back projection as well as the latest development of iterative algorithms, an appropriate number of kernels and multi-planar reconstruction in all directions from the volume data at every increment are available. Volume CT allows sub second scanning of 16cm z-coverage which, however, makes administration of intravenous contrast medium to "hit or miss" event. The aim of this paper is to present the application of volume CT to body scanning in children. Representative examples of neck, cardiac and skeletal investigations are given.

Perfusion CT in childhood stroke--initial observations and review of the literature.

INTRODUCTION: To report the preliminary results of contrast-enhanced perfusion multi-detector CT for diagnoses of perfusion disturbances in children with clinical suspicion of stroke. PATIENTS AND METHODS: Within the last two years emergency perfusion CT was performed in ten children (age: 8-17 years, male:female=3:7) for assessment of suspected childhood stroke. These intracranial perfusion CT, intracranial CT-digital subtraction angiography (CT-DSA) and extracranial CT-angiography (CTA) studies were retrospectively reviewed and compared with MRI, follow-up CT, catheter angiography and final clinical diagnosis. The total dose length product (DLP) for the entire examination was recorded. The image quality of perfusion CT-maps, CT-DSA and CTA were evaluated with a subjective three-point scale ranging from very good to non-diagnostic image quality rating perfusion disturbance, intracranial peripheral vessel depiction, and motion- or streak artifacts. RESULTS: In nine of ten children perfusion CT showed no false positive or false negative results. In one of ten children suffering from migraine focal hypo-perfusion was read as perfusion impairment potentially indicating early stroke, but MRI and MRA follow-up were negative. Overall, perfusion-CT with CT-DSA was rated very good in 80% of cases for the detection of perfusion disturbances and vessel anatomy. CONCLUSIONS: In comparison to standard CT, contrast-enhanced perfusion CT improves CTs' diagnostic capability in the emergency examination of children with a strong suspicion of ischemic cerebral infarction.

In vivo degradation performance of micro-arc-oxidized magnesium implants: a micro-CT study in rats.

Biodegradable Mg alloys are of great interest for osteosynthetic applications because they do not require surgical removal after they have served their purpose. In this study, fast-degrading ZX50 Mg-based implants were surface-treated by micro-arc oxidation (MAO), to alter the initial degradation, and implanted along with untreated ZX50 controls in the femoral legs of 20 male Sprague-Dawley rats. Their degradation was monitored by microfocus computed tomography (µCT) over a total observation period of 24weeks, and histological analysis was performed after 4, 12 and 24weeks. While the MAO-treated samples showed almost no corrosion in the first week, they revealed an accelerated degradation rate after the third week, even faster than that of the untreated ZX50 implants. This increase in degradation rate can be explained by an increase in the surface-area-to-volume ratio of MAO-treated implants, which degrade inhomogeneously via localized corrosion attacks. The histological analyses show that the initially improved corrosion resistance of the MAO implants has a positive effect on bone and tissue response: The reduced hydrogen evolution (due to reduced corrosion) makes possible increased osteoblast apposition from the very beginning, thus generating a stable bone-implant interface. As such, MAO treatment appears to be very interesting for osteosynthetic implant applications, as it delays implant degradation immediately after implantation, enhances fracture stabilization, minimizes the burden on the postoperatively irritated surrounding tissue and generates good bone-implant connections, followed by accelerated degradation in the later stage of bone healing.

Pediatric ovarian tumors--dilemmas in diagnosis and management.

BACKGROUND: Ovarian tumors are rare in the pediatric age group and thus diagnostic and treatment strategies are heterogeneous. This study aims to evaluate ovarian tumors with a focus on age at presentation, imaging characteristics, diagnostic strategy, tumor presentation and management. METHODS: Data was collected retrospectively from patients admitted between 1991 and 2008 for the evaluation and therapy of ovarian tumors. RESULTS: Twenty-five patients were identified with neoplastic ovarian lesions (mean age 10.7 years). Sixteen patients (64%) underwent surgery for benign and 9 (36%) for malignant tumors. Benign tumors (n=16) had a mean diameter of 10.7 cm and mean age at presentation was 9.6 years compared to a diameter of 18.6 cm and 12.3 years in the malignant group (n=9). Elevated tumor markers were observed in 3 (12.5%) benign tumors and in 7 (77.8%) malignant tumors. In preoperative ultrasound investigation, cyst formation was identified in 4 benign tumors and solid tumor mass in 2 malignant tumors. A minimally invasive surgical approach was chosen in two patients, while open surgery was opted for in the rest. CONCLUSION: Cyst formation, small tumor size and younger age at presentation were characteristic of benign tumors. Malignant tumors often presented with elevated tumor markers, a larger size and a solid consistency. Diagnostic dilemmas remain for both tumor groups due to the different tumor types and the heterogeneity of presentation.

Thick curved planar reformation of unenhanced multislice computed tomography demonstrating urolithiasis.

OBJECTIVES: To determine what slice thickness provides optimal curved planar reformation (CPR) images of the urinary tract. METHODS: A total of 75 consecutive patients with acute flank pain were included in a retrospective pilot study and underwent unenhanced multislice computed tomography (MSCT) (collimation 3.75 mm, pitch 6, reconstruction increment 3 mm, working voltage 120 kV, and tube current 100 mA) with CPR reconstruction of the urinary tract. CPRs with differing slice thicknesses of 3-20 mm at 1-mm increments to reformat each ureter were assessed in each patient separately. Two radiologists and a urologist evaluated the quality of the reformatted images by judging each ureter in terms of the delineation of all its parts using a 5-point scale (insufficient, poor, moderate, good, and excellent). RESULTS: Of the 75 patients in our cohort, 52 (69%) had urolithiasis. CPR images could be made of all ureters in all patients. Good to excellent image quality was found in the CPRs performed with a slice thickness of 8-12 mm: 27.7% at 8 mm, 14.3% at 9 mm, 26.9% at 10 mm, 12.6% at 11 mm, and 18.5% at 12 mm. Thus, a slice thickness of 8-12 mm determined a cumulative likelihood of 96.7% to demonstrate the ureter totally. CONCLUSIONS: The results of our study have shown that CPR is a feasible and quick useful tool. CPRs of the urinary tract with a slice thickness of 8-12 mm are best for good delineation of the whole ureter.

Comparison of 18F-FDG and 67Ga-citrate in sarcoidosis imaging.

AIM: (67)Ga citrate has been used long and successfully to diagnose and stage sarcoidosis. (18)F-fluorodeoxyglucose ((18)F-FDG) has been suggested as a positron emission tomography (PET) tracer for sarcoidosis imaging. This study aimed to analyze possible advantages of (18)F-FDG-PET over (67)Ga citrate scintigraphy during the primary assessment of patients with sarcoidosis. PATIENTS AND METHODS: Twenty-four patients (11 men, 13 women, aged 52 years +/-12.4) with histologically proven sarcoidosis were investigated with (18)F-FDG and (67)Ga citrate. Equipment included a full-ring PET scanner (ECAT EXACT HR+, Siemens/CTI, Knoxville TN, USA) and a double-headed gamma camera (ECAM, Siemens, Illinois, USA) for scintigraphy. The mean time difference between the two studies was 6.5 days (range: 5-8 days). RESULTS: There was a significant difference in the detection of pulmonary and nonpulmonary sarcoidosis lesions between planar (67)Ga citrate scans and (18)F-FDG-PET images (<0.0021). A total of 64 lesions were detected with (67)Ga citrate scans in the thorax and elsewhere with a mean of 2.6 lesions (4%) per patient, while 85 lesions were found with (18)F-FDG-PET, with a mean of 3.5 lesions (4.1%) per patient. There was complete agreement between (18)F-FDG and (67)Ga citrate in thoracic manifestations in four (16.6%) patients, and in non-thoracic manifestations in five (20.8%) patients. The interobserver variability showed a kappa value of 0.79. CONCLUSION: (67)Ga citrate and (18)F-FDG are useful tracers for diagnostic evaluation of thoracic sarcoidosis. (18)F-FDG seems to be more suitable for imaging the mediastinum, the bi-hilar lymph nodes, the posterior regions of the lungs and non-thoracic lesions. Further prospective studies are needed to clarify the role of both tracers in early diagnosis and staging of sarcoidosis, and to resolve questions concerning medical treatment and follow-up.

[3D cross section of the laryngotracheal tract. A new method for visualization and quantification of tracheal stenoses]. / 3D-Querschnittsprofil des Laryngotrachealtrakts. Eine neue Methode zur Visualisierung und Quantifizierung von Trachealstenosen.

PURPOSE: Demonstration of a technique for 3D assessment of tracheal stenoses, regarding site, length and degree, based on spiral computed tomography (S-CT). PATIENTS AND METHODS: S-CT scanning and automated segmentation of the laryngo-tracheal tract (LTT) was followed by the extraction of the LTT medial axis using a skeletonisation algorithm. Orthogonal to the medial axis the LTT 3D cross sectional profile was computed and presented as line charts, where degree and length were obtained. Values for both parameters were compared between 36 patients and 18 normal controls separately. Accuracy and precision was derived from 17 phantom studies. RESULTS: Average degree and length of tracheal stenoses were found to be 60.5% and 4.32 cm in patients compared to minor caliber changes of 8.8% and 2.31 cm in normal controls (p <0.005). For the phantoms an excellent correlation between the true and computed 3D cross sectional profile was found (p <0.005) and an accuracy for length and degree measurements of 2.14 mm and 2.53% respectively could be determined. The corresponding figures for the precision were found to be 0.92 mm and 2.56%. CONCLUSION: LTT 3D cross sectional profiles permit objective, accurate and precise assessment of LTT caliber changes. Minor LTT caliber changes can be observed even in normals and, in case of an otherwise normal S-CT study, can be regarded as artefacts.

18F-FDG PET: early postoperative period of oro-maxillo-facial flaps.

AIM: We addressed the feasibility of FDG-PET to differentiate between viability and non-viability in the immediate postoperative assessment of flaps (autologous microvascular anastomosed pedicled flaps) in oro-maxillo-facial surgery. METHODS: 3-7 days after surgery, FDG-PET was done in 38 patients who had received flaps for re-construction of the mandible after partial resection. The studies were done on a dedicated full ring PET-scanner (ECAT EXACT HR+, Siemens/CTI). Acquisition started between 60 and 80 min post injection. The findings of the soft tissue component of the flaps were grouped using a three point scale: (I) no defect, (II) small defects, (III) one large defect. The results of PET were compared with the clinical course for at least 3 months. RESULTS: "No defect" on the FDG-PET study identified vi-ability of the flap and predicted normal clinical follow-up (22/38 patients). "Small defects" visualized areas of decreased perfusion and decreased glucose metabolism indicating risk of non-viability (13/38 patients); adapt-ing the postsurgical management led to delayed but uncomplicated healing of the flaps in these patients. "One large defect" demonstrated early necrosis of the flap (3/38 patients). After removal and replacement of this necrotic portion of the flap the second FDG-PET scan of these 3 patients demonstrated the uncomplicated post-operative healing. CONCLUSION: FDG-PET facilitated the assessment of viability and non viability of flaps in the immediate postsurgical period, and demonstrated the usefulness of FDG-PET for postoperative care and prognosis.

Imaging guided interventional procedures in paediatric uroradiology--a case based overview.

OBJECTIVE: To describe the potential and application of interventional image guided procedures in the paediatric urinary tract. PATIENTS AND METHODS: The different techniques are illustrated using case reports. The examples comprise established indications such as percutaneous nephrostomy for compromised kidneys in obstructive uropathy and infection, sonographic guided renal biopsy including monitoring or treatment of complications after biopsy, and evaluation and balloon dilatation of childhood renal artery stenosis. There are new applications such as treatment of stenosis in cutaneous ureterostomy or sonographically guided catheterism for deployment of therapeutic agents. RESULTS: Generally, the procedures are safe and successful. However, complications may occur, and peri-/post-interventional monitoring is mandatory to insure early detection and adequate management. Sometimes additional treatment such as percutaneous embolisation of a symptomatic post biopsy arterio-venous fistula, or a second biopsy for recurrent disease may become necessary. CONCLUSION: Imaging guided interventional procedures are performed successfully in a variety of diseases of the paediatric urinary tract. They can be considered a valuable additional modality throughout infancy and childhood.

[Nontraumatic injury (battered child)]. / Die nicht unfallbedingte Verletzung (battered child).

The recognition of a battered child represents a challenge for all groups of adults dealing with children. Radiology plays a special role in this setting. By detection typical injuries, imaging is able to confirm the suspicion of a battered child. Recognition of those injuries on films, taken for other reasons, gives the caretaker an important hint, thus maybe preventing a fatal outcome for the child. One of the most important injury types is represented by the so called "shaken baby syndrome". The infant is held by the thorax and shaken. Thus causing a repetitive acceleration-deceleration trauma, which leads to the typical paravertebral rib fractures, intracranial bleeding and eye injuries. After shaking the child is thrown away, with subsequent injuries. The aim of this article is the presentation of an overview regarding the radiology of the battered child. Typical examples will be shown.

Helical CT angiography with maximum intensity projection in the assessment of aortic coarctation after surgery.

OBJECTIVE: The value of CT angiography and three-dimensional (3D) reconstructions was investigated in the postoperative care after surgical repair of aortic coarctation and compared with conventional angiography. SUBJECTS AND METHODS: Twenty-five patients referred because of suspicion of stenosis in the area of former coarctation were prospectively studied with CT angiography and catheter angiography. We determined the morphometric and morphologic findings such as aortic diameter, stenosis, aneurysm, intimal flaps, circumscribed pouch, or arteriosclerotic plaques with 3D reconstructions, using maximum-intensity-projection (MIP) technique and catheter angiography. The results of both techniques were compared. The ratio of the narrowest diameters of the former coarctation and the descending aorta was correlated with the systolic pullback blood pressure gradient in all patients. RESULTS: The former coarctation was normal in 11 patients, (44%), group A; narrowed in 12 children (48%), group B; and dilated in two children (8%), group C. An intimal flap and a circumscribed pouch were delineated in four subjects. MIP reconstructions and catheter angiography revealed identical results regarding the classification into groups A, B, C; intimal flaps; and circumscribed pouches. Statistical analysis revealed good correlation between the narrowest aortic diameters measured on MIP reconstructions and catheter angiography, whereas no correlation between the systolic pullback blood pressure gradient and the diameter ratio of the former coarctation and the descending aorta was found. CONCLUSION: CT angiography and 3D reconstructions using MIP represent a reliable noninvasive technique to replace diagnostic catheter angiography in the postoperative care of patients with coarctation and provide the clinician with valuable information concerning further invasive procedures.

CT findings in post-operative subphrenic abscess with teratomatous inclusions.

A 39-year-old woman presented with abdominal pain after tubal sterilization. CT showed a subphrenic abscess with fatty inclusions owing to laceration or rupture of a mature ovarian teratoma. Although subphrenic abscess is a well recognized post-operative complication, and ovarian teratomas are frequent, a teratomatous inclusion within a subphrenic abscess is a unique finding.

Gastroesophageal reflux and diaphragmatic motility after repair of congenital diaphragmatic hernia.

At the Department of Pediatric Surgery in Graz, 31 boys and 23 girls were operated on for congenital diaphragmatic hernia (CDH) from 1978 to 1994. In 49 patients the defect was on the left, in five on the right side. In 46 cases, the hernia was diagnosed within the first week of life; in eight children at a later date. 19 children (35%) died. 25 of the 35 survivors (71%) came to a follow-up examination on average 9.4 (1-17) years after the operation. 24 h pH-monitoring or manometry and Upper G.I. series revealed pathological gastroesophageal reflux (GER) in 16 patients. Nine children were treated conservatively; in seven patients an antireflux procedure was performed. A thoracic position of the stomach or left liver lobe, presence of a hernial sac, gestational age, prenatal diagnosis, use of a patch or severity of lung hypoplasia did not significantly influence the incidence of GER. In three patients, a hiatal hernia was found. The motility of the diaphragm was documented with M-mode sonography (n = 18); a restricted motility could be demonstrated in five patients. GER is very common in patients after repair of CDH. We recommend long-term follow-up with special interest in respect of GER.

3-D image analysis of abdominal aortic aneurysm.

In this paper we propose a technique for 3-D segmentation of abdominal aortic aneurysm (AAA) from computed tomography (CT) angiography images. Output data form the proposed method can be used for measurement of aortic shape and dimensions. Knowledge of aortic shape and size is very important for selection of appropriate stent graft device for treatment of AAA. The technique is based on a 3-D deformable model and utilizes the level-set algorithm for implementation of the method. The method performs 3-D segmentation of CT images and extracts a 3-D model of aortic wall. Once the 3-D model of aortic wall is available it is easy to perform all required measurements for appropriate stent graft selection. The method proposed in this paper uses the level-set algorithm instead of the classical active contour algorithm developed by Kass et al. The main advantage of the level set algorithm is that it enables easy segmentation surpassing most of the drawbacks of the classical approach. In the level-set approach for shape modeling, a 3-D surface is represented by a real 3-D function or equivalent 4-D surface. The 4-D surface is then evolved through an iterative process of solving the differential equation of surface motion. Surface motion is defined by velocity at each point. The velocity is a sum of constant velocity and curvature-dependent velocity. The stopping criterion is calculated based on image gradient. The algorithm has been implemented in MATLAB and C languages. Experiments have been performed using real patient CT angiography images and have shown good results.

An automatic method for the identification and interpretation of clustered microcalcifications in mammograms.

We investigated a method for a fully automatic identification and interpretation process for clustered microcalcifications in mammograms. Mammographic films of 100 patients containing microcalcifications with known histology were digitized and preprocessed using standard techniques. Microcalcifications detected by an artificial neural network (ANN) were clustered and some cluster features served as the input of another ANN trained to differentiate between typical and atypical clusters, while others were fed into an ANN trained on typical clusters to evaluate these lesions. The measured sensitivity for the detection of grouped microcalcifications was 0.98. For the task of differentiation between typical and atypical clusters an Az value of 0.87 was computed, while for the diagnosis an Az value of 0.87 with a sensitivity of 0.97 and a specificity of 0.47 was obtained. The results show that a fully automatic computer system was developed for the identification and interpretation of clustered microcalcitications in mammograms with the ability to differentiate most benign lesions from malignant ones in an automatically selected subset of cases.