Ventilation inhomogeneity in obstructive lung diseases measured by electrical impedance tomography: a simulation study.

Electrical impedance tomography (EIT) has mostly been used in the Intensive Care Unit (ICU) to monitor ventilation distribution but is also promising for the diagnosis in spontaneously breathing patients with obstructive lung diseases. Beside tomographic images, several numerical measures have been proposed to quantitatively assess the lung state. In this study two common measures, the 'Global Inhomogeneity Index' and the 'Coefficient of Variation' were compared regarding their capability to reflect the severity of lung obstruction. A three-dimensional simulation model was used to simulate obstructed lungs, whereby images were reconstructed on a two-dimensional domain. Simulations revealed that minor obstructions are not adequately recognized in the reconstructed images and that obstruction above and below the electrode plane may result in misleading values of inhomogeneity measures. EIT measurements on several electrode planes are necessary to apply these measures in patients with obstructive lung diseases in a promising manner.

Simultaneous application of two independent EIT devices for real-time multi-plane imaging.

Diagnosis and treatment of many lung diseases like cystic fibrosis (CF) or chronic obstructive pulmonary disease (COPD) could benefit from 3D ventilation information. Applying two EIT systems concurrently is a simple approach without specialized hardware that allows monitoring of regional changes of ventilation distribution inside the thorax at different planes with the high temporal resolution much valued in common single plane EIT. Effects of two simultaneously operated EIT devices on one subject were investigated to monitor rapid processes inside the thorax with a multi-plane approach. Results obtained by simulations with a virtual phantom and measurements with a phantom tank reveal that the distance of electrode planes has an important influence on the signal quality. Band-pass filters adapted according to the distance of the planes, can be used to reduce the crosstalk of the concurrent EIT systems. Besides simulations and phantom tank experiments measurements were also taken from a lung healthy volunteer to demonstrate the operation under realistic conditions. Reconstructed images indicate that it is possible to simultaneously visualize regional ventilation at different planes if settings of the EIT devices are chosen appropriately.

Compensation for large thorax excursions in EIT imaging.

Besides the application of EIT in the intensive care unit it has recently also been used in spontaneously breathing patients suffering from asthma bronchiole, cystic fibrosis (CF) or chronic obstructive pulmonary disease (COPD). In these cases large thorax excursions during deep inspiration, e.g. during lung function testing, lead to artifacts in the reconstructed images. In this paper we introduce a new approach to compensate for image artifacts resulting from excursion induced changes in boundary voltages. It is shown in a simulation study that boundary voltage change due to thorax excursion on a homogeneous model can be used to modify the measured voltages and thus reduce the impact of thorax excursion on the reconstructed images. The applicability of the method on human subjects is demonstrated utilizing a motion-tracking-system. The proposed technique leads to fewer artifacts in the reconstructed images and improves image quality without substantial increase in computational effort, making the approach suitable for real-time imaging of lung ventilation. This might help to establish EIT as a supplemental tool for lung function tests in spontaneously breathing patients to support clinicians in diagnosis and monitoring of disease progression.

MRI of the Prostate in Germany: Online Survey among Radiologists.

PURPOSE: To assess structural, technical, and communicative aspects of dedicated MR examinations of the prostate (MRP) offered by radiologists in Germany. MATERIALS AND METHODS: We conducted an eight-item online survey among members of the German Radiology Society (DRG). Radiological institutions were asked about their structure, i.e., either hospital department (HD) or private practice (PP), number of board-certified radiologists, postal regions, number of MRPs in 2011, MR technology and MR sequences applied, ways to communicate results, and feedback from referring physicians on results of subsequent tests and procedures. Submissions were cleared of redundancies and anonymized. Differences in the number of positive replies to each item were statistically significant at p < 0.05 for two-tailed testing in 2 x 2 tables. RESULTS: The survey represented board-certified radiologists in 128 institutions (63 HDs and 65 PPs) in 67/95 German postal regions (71%). Almost two-thirds of institutions performed 11 to 50 MRPs in 2011, more often at 1.5 T (116/128, 91%) than at 3.0 T (36/128, 28%), and most frequently with surface coils (1.5 T, 88/116, 76%; 3.0 T, 34/36, 94%; chi-square, 1.9736, 0.1 < p < 0.25). About two-thirds of 1.5 T users and 90% of 3.0 T users applied at least one functional MR modality (diffusion-weighted imaging, dynamic contrast-enhanced imaging, or MR spectroscopy) for MRP. Reports including graphic representations of the prostate were applied by 21/128 institutions (16%). Clinical feedback after MRP to radiologists other than upon their own request was infrequent (HDs, 32-45%, PPs, 18-32%). CONCLUSION: MRP was a widely available, small-volume examination among radiologists in Germany in 2011. The technology mainstay was a 1.5 T surface coil examination including at least one functional MR modality. Dedicated reporting and feedback mechanisms for quality control were underdeveloped. KEY POINTS: MRI of the prostate was available in at least 67 of 95 German postal regions (71%) in 2011. MRI of the prostate was most often performed at 1.5 T without an endorectal coil in Germany in 2011. At least two thirds of MRI-examinations of the prostate included both T2WI and at least one functional MR test (mostly DWI, less frequently MRS or DCE) in Germany in 2011. Structured reporting including graphic elements was offered by less than 20% of participating radiological institutions. Feedback to radiologists from referring physicians on subsequent test results in patients with MRI of the prostate most frequently came only upon special request by the radiologist.

Cystic fibrosis in adults: short-term and long-term reproducibility of the Brody score for lung morphology in low-dose MDCT scans.

PURPOSE: The semi-quantitative Brody score measures the severity of cystic fibrosis (CF)-related lung disease. We investigated the short-term (28 - 60 days) and long-term (2 - 7 years) intra- and inter-observer reproducibility of the Brody score in low-dose multidetector row computed tomography examinations performed in inspiration (LDCTs) of adult CF patients. MATERIALS AND METHODS: Composite Brody scores and respective underlying bronchiectasis, mucus plugging, peribronchial thickening, parenchymal opacity, and hyperinflation subscores were evaluated twice (time interval, 1 - 84 months) by each of 3 independent radiologists (1 - 20 years of professional diagnostic radiology experience) in LDCTs (4 - 64 rows, 120 KVp, 10 - 15  mAs/slice, CTDIw approx. 1.0  mGy, effective dose approx. 0.5  mSv) of 15 adult patients with CF-related lung disease (8 female, 7 male, age, 18 - 50 years, mean, 33 years). RESULTS: The average reproducibility of the Brody score was within +/-7 % (range, 2 - 30 %) between radiologists, and +/-6 % (3 - 12 %) within radiologists (short-term, 28 - 60 days, 4 %, 0 - 12 %, long-term, 2 - 7 years, 12 %, 1 - 36 %). For the different subscores, the reproducibility was within +/-25 % (15 - 41 %) between radiologists and +/-23 % (12 - 46 %) within radiologists. CONCLUSION: The Brody score shows high average inter-observer reproducibility in LDCTs of adult CF patients. The Brody score also demonstrates high average intra-observer reproducibility if subsequent assessments are made within 28 - 61 days. With time intervals of 2 - 7 years between subsequent evaluations, however, intra-observer reproducibility decreases. Respective subscores each demonstrate lower intra- and inter-observer reproducibility than does the composite Brody score.

[CT urography in women with primary or recurrent pelvic tumors : background and initial experiences]. / CT-Urographie bei Frauen mit primären oder rezidivierenden Beckentumoren : Hintergrund und erste Erfahrungen.

Malignant tumors of the female pelvis account for 12-13% of newly diagnosed solid neoplasms among women in the USA and Germany. German guidelines advocate diagnostic imaging for local recurrence and metastasis while there are no recommendations for primary tumors. As excretory urography has been replaced by the excretory phase of computed tomography urography (CTU) in many institutions, two independent observers retrospectively evaluated CTUs of primary or recurrent female pelvic tumors to rule out associations between CTU findings and subsequent urologic measures. Among 31 CTUs of 27 women (age 29-84 years, mean 57 years) with 15 primary and 13 recurrent tumors, 83-100% of unremarkable proximal, middle and distal ureter segments were completely delineated in the excretory phase (delay 6-29 min, mean 16 min). The most common pathological findings included distal ureter obstruction (n=19, 61%), bladder compression (n=13, 42%) and bladder invasion (n=8, 26%). Out of 20 pathologically altered urinary tracts 8 were subsequently subjected to urologic measures (2-tailed Fisher exact test, p=0.0215) but none of the 10 unremarkable urinary tracts were treated. It appears that CTU is a sensible pre-therapeutic test for the urinary tract for primary and recurrent female pelvic tumors.

[Diffusion-weighted MRI of the prostate]. / Diffusionsgewichtete MRT der Prostata.

Diffusion-weighted magnetic resonance imaging (DWI) can complement MRI of the prostate in the detection and localization of prostate cancer, particularly after previous negative biopsy. A total of 13 original reports and 2 reviews published in 2010 demonstrate that prostate cancer can be detected by DWI due to its increased cell density and decreased diffusiveness, either qualitatively in DWI images or quantitatively by means of the apparent diffusion coefficient (ADC). In the prostate, the ADC is influenced by the strength of diffusion weighting, localization (peripheral or transitional zone), presence of prostatitis or hemorrhage and density and differentiation of prostate cancer cells. Mean differences between healthy tissue of the peripheral zone and prostate cancer appear to be smaller for ADC than for the (choline + creatine)/citrate ratio in MR spectroscopy. Test quality parameters vary greatly between different studies but appear to be slightly better for combined MRI and DWI than for MRI of the prostate alone. Clinical validation of DWI of the prostate requires both increased technical conformity and increased numbers of patients in clinical studies.

[An unusual case of non-traumatic enophthalmos]. / Ungewöhnlicher Fall eines atraumatischen Enophthalmus.

An extensive spectrum of differential diagnoses has to be considered when a patient presents with enophthalmos. The most common causes of this presentation include orbital trauma or contraction and atrophy of the orbital contents secondary to scleroderma or radiotherapy. However radiologists also have to consider less common causes of enophthalmos, such as the imploding antrum syndrome or the ethmoid silent sinus syndrome. The latter involves the ethmoidal cells and results in medial orbital wall implosion. Along with the case presentation the pathogenesis, incidence and differential diagnoses of ethmoid silent sinus syndrome are elucidated. In particular the differentiation from normal anatomical variants, such as dehiscent lamina papyracea is discussed.

[Imaging modalities for primary diagnosis and staging of prostate cancer]. / Bildgebende Verfahren bei Primärdiagnose und Staging des Prostatakarzinoms.

The new S3 guideline on prostate cancer includes imaging modalities applied for early detection, primary diagnosis, and staging of prostate cancer. Detection and primary diagnosis are based on digital rectal examination, serum PSA levels, and prostate biopsy. Among the imaging modalities, MRI shows the highest test quality parameters. Although MRI cannot replace biopsy to prove prostate cancer, its high negative predictive value can help to reduce the number of subsequent biopsies after negative prostate biopsy. For T-staging, MRI also demonstrates the highest test quality parameters. Its clinical application is limited, since therapeutic consequences are restricted. Due to its high specificity, MRI can save unnecessary pelvic lymph node dissections in patients at high risk for lymph node metastasis (N-staging). Risk-adjusted bone scans, complemented by additional radiological examinations if necessary, remain the standard to assess hematogenous metastasis (M staging).

Catheter-based intraluminal optical coherence tomography versus endoluminal ultrasonography of porcine ureter ex vivo.

OBJECTIVES: To compare the distinction of tissue layers of porcine ureters ex vivo between optical coherence tomography (OCT) and endoluminal ultrasonography (ELUS). Catheter-guided OCT is a new method of intraluminal microstructural imaging, with a spatial resolution of 10-20 mum. METHODS: Porcine ureters and kidneys were obtained fresh from the municipal slaughtery, cannulated with a 7F catheter sheath, flushed with normal saline solution, and marked on the outside with surgical suture. Between the marked positions, images were obtained from within the ureter lumen using OCT (M1, Lightlab, Westport, MA) and ELUS at 40 MHz. The distinction of the urothelium, lamina propria, and inner and outer muscle layers was rated as possible (1) or impossible (0) by 2 independent observers (O1, O2). The rates of distinction were compared between OCT and ELUS image quadrants using the chi(2) test. RESULTS: Of the 224 OCT image quadrants and 144 ELUS image quadrants, OCT was superior to ELUS in the distinction of any wall layers (O1, chi(2)P = 68.1051, P < .001; O2, chi(2)P = 66.1630, P < .001), urothelium and lamina propria (O1, chi(2)P = 200.0750, P < .001; O2, chi(2)P = 240.0024, P < .001), and lamina propria and muscle layer (O1, chi(2)P = 38.8411, P < .001; O2, chi(2)P = 24.7536, P < .001) but was inconclusive for the inner and outer muscle layer (O1, chi(2)P = 260.3004, P < .001; O2, chi(2)P = 0.4992, P > .25). CONCLUSIONS: OCT was able to distinguish significantly better than ELUS between different wall layers of porcine ureter ex vivo. The feasibility of OCT in vivo and in the presence of pathologic wall thickening of the ureter remains to be demonstrated.

Intracranial germinoma as a very rare cause of panhypopituitarism in a 23-year old man.

A 23 year-old patient was referred to the endocrine outpatient clinic with the suspicion of diabetes insipidus as he complained of nycturia and polydipsia since 2-3 months. Further he presented with nausea, vomiting, loss of appetite, rapid weight loss, diffuse body pain and fatigue. No headache, blurred vision, or fever were reported. The clinical examination showed sexual infantilism (poor beard, pubic and axillary hair growth, small testis). The patient's skin was strikingly pale as well as dry and scaly. Lymph node palpation was unremarkable. Endocrine evaluation revealed diabetes insipidus as well as complete anterior pituitary insufficiency. MR imaging demonstrated contrast-enhancing mass lesions at the pineal gland, hypothalamus, and anterior horn of lateral ventricles bilaterally. The localization pattern deemed to be highly suspicious for intracranial germinoma. As beta-HCG and AFP were negative in serum and cerebrospinal fluid the diagnosis of germinoma was confirmed histologically. After radiotherapy with cranio-spinal radiation therapy with 24 Gy followed by two weeks of local tumor boost with 16 Gy, the posttherapy MRI scan indicated complete tumor removal. This case demonstrates a very rare and potentially curable tumor as the cause of panhypopituitarism in adults.

[Cross-sectional imaging in dentomaxillofacial diagnostics: dose comparison of dental MSCT and NewTom 9000 DVT]. / Schnittbildverfahren zur dentomaxillofazialen diagnostik: dosisvergleich von dental-MSCT und NewTom 9000 DVT.

PURPOSE: For nonsuperimposed and three-dimensional imaging of jaws and teeth, multislice computer tomography (MSCT) can be performed, or alternatively digital volume tomography as a cone beam technique can be applied. The radiation dose of both procedures should be evaluated with different methods of dose assessment. MATERIALS AND METHODS: A 4-row MSCT (Volume Zoom Siemens) and a cone beam CT (NewTom QR-DVT 9000) were compared regarding the radiation exposure of the patient during a dental examination. Organ dose and effective dose were estimated by thermoluminescence dosimetry (TLD) using an Alderson-Rando phantom for both devices. In addition the effective dose of MSCT was calculated from the CTDIvol-value at scanner display and by CT-Expo program. RESULTS: The effective dose of MSCT was 0.33 mSv for women (w) and 0.32 mSv for men (m) measured with TLD in the Alderson-Rando phantom, 0.39 / 0.35 mSv (w/m) by CTDI calculation and 0.39 / 0.33 mSv by CT-Expo program. The effective dose of NewTom QR-DVT 9000 from TLD measurement was 0.095 / 0.093 mSv (w/m). CONCLUSION: The radiation exposure of a typical dental examination with a NewTom cone beam DVT is about one third of the MSCT dose. Both techniques, however, moderate patient doses. Dosimetry methods as routinely used for MSCT cannot be applied to cone beam DVT.

Beam hardening artefacts occur in dental implant scans with the NewTom cone beam CT but not with the dental 4-row multidetector CT.

OBJECTIVES: The aim of this study was to examine beam hardening artefacts of the NewTom 9000 cone-beam computed tomography (CBCT) device compared with the Philips MX 8000 (4-row multidetector CT (MDCT)). METHODS: We modified a SawBone skull to become a standardized model for our study. The skull was used for scans with the NewTom 9000 CBCT device and a standard dental multi-detector CT (MDCT) at a comparable reconstruction resolution with a standard Straumann ITI 4.1 mm implant in four implant positions in the maxilla (first permanent premolar in the right maxilla region, second permanent molar in the right maxilla region, first permanent premolar in the left maxilla region and second permanent molar in the left maxilla region). Results were compared with construction data of the dental implant. An image quality assessment of the images from both devices was performed with four experienced physicians and statistically analysed with the two-tailed Wilcoxon test. RESULTS: Scans with the NewTom 9000 CBCT showed strong beam hardening artefacts in the form of a radiation beam shadow in all reconstructions compared with the MDCT. These imaging artefacts became stronger with greater distance from the centre of the scanned volume. These differences in the imaging quality were proved as significant in a quality evaluation by four experienced physicians (P<0.05). CONCLUSIONS: Visual spatial resolution of the NewTom 9000 CBCT was less accurate than the Philips MX 8000 MDCT in the imaging of metallic dental implants.

Perforation of the colon: a rare complication of hepatocellular carcinoma.

Direct infiltration of the colon by hepatocellular carcinoma (HCC) is a rare condition. Only a few reports can be found in the literature. Here we present a case of direct infiltration of the ascending colon by an exophytic growing HCC of the right posterior liver lobe, in which treatment with transarterial chemoembolization (TACE) had been performed. Tumor invasion became evident by abdominal pain and lower gastrointestinal bleeding. Diagnosis was established by contrast-enhanced multidetector computed tomography (CE-MDCT), demonstrating the direct tumor invasion with concomitant perforation of the infiltrated colon segment. Based on these findings, rapid and effective surgical treatment could be achieved.

[33 year old Libanese woman with recurrent haemoptysis and cystic lesion of the lung]. / 33-jährige Libanesin mit rezidivierenden Hämoptysen und zystischer Raumforderung in der Lunge.

A 33 year old woman from Lebanon presented with recurrent hemoptysis, subfebrile temperature, dyspnoe in stress, fatigue, weight loss, and pruritus. Serological tests and results from chest X-ray and computer tomography revealed cystic echinococcosis with pulmonary involvement. After refusal of surgical therapy a medical treatment with albendazole was implemented. Two months after the start of the therapy only a small fibrotic residuum in the lung was seen. A spontaneous healing success seems unlikely because of the duration of the pulmonary cyst and the progressive symptoms before treatment.

Multidetector CT of the kidney.

The technological development of multidetector CT offers new possibilities for better imaging of organic structures that can be used in diagnosis of the kidney. The thinner slices allow a better spatial resolution, and slice fusion allows improved contrast resolution. The isotropic voxel has been realized in the latest 64-channel scanners. The image quality of arbitrarily reconstructed planes has arrived at the image quality of the scan plane. Faster scanning allows studies in different contrast phases, which is helpful for better discrimination of benign or malignant lesions especially in the highly vascularized kidney. Different phases of contrast uptake can be differentiated (arterial, cortico-medullary, nephrographic, and excretory phase). Multidetector CT brings along the risk of increased dose due to thinner slice collimation and overranging phenomena. Indications for CT investigation of the kidney include urolithiasis, tumor diagnosis and staging, renal trauma, and vascular disease. Even in children, special indications for CT of the kidney remain in polytrauma and tumor staging. Multidetector CT of the kidney has become a very valuable tool in urology, but a careful protocol strategy is mandatory.

Dose reduction in multidetector CT of the urinary tract. Studies in a phantom model.

A novel ureter phantom was developed for investigations of image quality and dose in CT urography. The ureter phantom consisted of a water box (14 cm x 32 cm x 42 cm) with five parallel plastic tubes (diameter 2.7 mm) filled with different concentrations of contrast media (1.88-30 mg iodine/ml). CT density of the tubes and noise of the surrounding water were determined using two multidetector scanners (Philips MX8000 with four rows, Siemens Sensation 16 with 16 rows) with varying tube current-time product (15-100 mAs per slice), voltage (90 kV, 100 kV, 120 kV), pitch (0.875-1.75), and slice thickness (1 mm, 2 mm, 3.2 mm). Contrast-to-noise ratio as a parameter of image quality was correlated with dose (CTDI) and was compared with image evaluation by two radiologists. The CT densities of different concentrations of contrast media and contrast-to-noise ratio were significantly higher when low voltages (90 kV versus 120 kV, 100 kV versus 120 kV) were applied. Smaller slice thickness (1 mm versus 2 mm) did not change CT density but decreased contrast-to-noise ratio due to increased noise. Contrast phantom studies showed favourable effects of low tube voltage on image quality in the low dose range. This may facilitate substantial dose reduction in CT urography.

[Intravascular optical coherence tomography: differentiation of atherosclerotic plaques and quantification of vessel dimensions in crural arterial specimens]. / Intravaskuläre optische Kohärenztomographie: Unterscheidung verschiedener Plaquetypen und Vermessung von Gefässdimensionen in atherosklerotischen Unterschenkelarterien.

PURPOSE: Intravascular optical coherence tomography (OCT) is a new technique based on infrared light that visualizes the arteries with a resolution of 10-20 microm. Intravascular ultrasound (IVUS) is the current in vivo reference standard and provides a resolution of 100-150 microm. This study compared OCT to IVUS and histopathology with respect to the ability to differentiate atherosclerotic plaques and quantify vascular dimensions in peripheral crural arteries ex vivo. MATERIALS AND METHODS: 50 segments of atherosclerotic arteries derived from five amputated human lower extremities were examined. The different plaque types (fibrous, high-lipid content, calcified) were assigned by two independent examiners, and the sensitivity and specificity of OCT in comparison with histopathology as well as intra- and interobserver consensus were calculated. A comparison of OCT with IVUS addressed the parameters: luminal area (LA), vascular wall area (VA) and plaque area (PA). RESULTS: When comparing OCT and histopathology with respect to the differentiation of various plaque types, sensitivities of 81 % and specificities of 89 % for fibrous plaques, of 100 % and 93 % for lipid-rich plaques and of 80 % and 89 % for calcified plaques were achieved (overall correlation 83 %). Intra- and interobserver consensus was very high (kappa = 0.86 and kappa = 0.89, p < 0.001, respectively). There was also a high correlation between quantitative measurements (Bland-Altman plot [LA]: mean bias, 0.1 mm(2) accuracy +/- 1.8 mm(2), r = 0.95 [p < 0.001] Bland-Altman plot [VA]: mean bias, 0.3 mm(2) accuracy +/- 2.3 mm(2), r = 0.94 [p < 0.001] Bland-Altman plot [PA]: mean bias, 0.4 mm(2) accuracy +/- 2.3 mm(2), r = 0.80 [p < 0.01]. CONCLUSION: OCT allows the differentiation of atherosclerotic plaque types in crural arteries with high accuracy compared to histopathology. Quantitative measurements show a high correlation with IVUS, the current reference standard.