Detection and size measurements of kidney stones on virtual non-contrast reconstructions derived from dual-layer computed tomography in an ex vivo phantom setup.

OBJECTIVES: To systematically investigate the usability of virtual non-contrast reconstructions (VNC) derived from dual-layer CT (DLCT) for detection and size measurements of kidney stones with regards to different degrees of surrounding iodine-induced attenuation and radiation dose. METHODS: Ninety-two kidney stones of varying size (3-14 mm) and composition were placed in a phantom filled with different contrast media/water mixtures exhibiting specific iodine-induced attenuation (0-1500 HU). DLCT-scans were acquired using CTDIvol of 2 mGy and 10 mGy. Conventional images (CI) and VNC0H-1500HU were reconstructed. Reference stone size was determined using a digital caliper (Man-M). Visibility and stone size were assessed. Statistical analysis was performed using the McNemar test, Wilcoxon test, and the coefficient of determination. RESULTS: All stones were visible on CI0HU and VNC200HU. Starting at VNC400 HU, the detection rate decreased with increasing HU and was significantly lower as compared to CI0HU on VNC≥ 600HU (100.0 vs. 94.0%, p < 0.05). The overall detection rate was higher using 10 mGy as compared to 2 mGy protocol (87.9 vs. 81.8%; p < 0.001). Stone size was significantly overestimated on all VNC compared to Man-M (7.0 ± 3.5 vs. 6.6 ± 2.8 mm, p < 0.001). Again, the 10 mGy protocol tended to show a better correlation with Man-M as compared to 2 mGy protocol (R2 = 0.39-0.68 vs. R2 = 0.31-0.57). CONCLUSIONS: Detection and size measurements of kidney stones surrounded by contrast media on VNC are feasible. The detection rate of kidney stones decreases with increasing iodine-induced attenuation and with decreasing radiation dose as well as stone size, while remaining comparable to CI0HU on VNC ≤ 400 HU. KEY POINTS: • The detection rate of kidney stones on VNC depends on the surrounding iodine-induced attenuation, the used radiation dose, and the stone size. • The detection rate of kidney stones on VNC decreases with greater iodine-induced attenuation and with lower radiation dose, particularly in small stones. • The visibility of kidney stones on VNC ≤ 400 HU remains comparable to true-non-contrast scans even when using a low-dose technique.

Head and neck squamous cell carcinoma: evaluation of iodine overlay maps and low-energy virtual mono-energetic images acquired with spectral detector CT.

AIM: To evaluate the diagnostic value of spectral detector computed tomography (SDCT)-derived iodine overlay maps and low-energy virtual mono-energetic images (VMI) for the initial locoregional assessment of primary, therapy-naive head and neck cancer. MATERIALS AND METHODS: Fifty-six patients with histologically confirmed untreated squamous cell carcinoma of the head and neck who underwent SDCT of the neck for staging purposes were included in this retrospective study. Attenuation, image noise as well as signal- and contrast-to-noise ratios (S-/CNR) in VMI40-70keV were obtained from region of interest (ROI)-based measurements in the tumour and important anatomical landmarks (sternocleidomastoid muscle, subcutaneous fat, thyroid gland, submandibular gland, carotid artery, and jugular vein). Tumour conspicuity and delineation, as well as subjective image quality, were rated for conventional images, VMI40-70keV, and iodine overlay maps using five-point Likert scales. RESULTS: The CNR of the tumour versus the floor of the mouth and the CNR of the tumour versus the sternocleidomastoid muscle was significantly higher in VMI40keV in comparison to conventional images (10.0 ± 7.3 versus 3.8 ± 3.3 and 11.3 ± 7.6 versus 3.6 ± 2.8; p<0.05 each). This was supported by qualitative results, as tumour conspicuity and delineation received superior ratings in iodine overlay maps and VMI40keV compared to conventional images (5 [3-5] and 5 [4-5] versus 3 [2-5]; 5 [2-5] and 5 [3-5] versus 3 [2-4], respectively, all p<0.05). VMI40keV yielded the highest score among all included image reconstructions for overall image quality (p<0.05 all). CONCLUSION: Iodine overlay maps and low-energy VMI derived from SDCT improve initial assessment of primary squamous cell carcinoma of the head and neck compared to conventional images.

Evaluating anemia using contrast-enhanced spectral detector CT of the chest in a large cohort of 522 patients.

OBJECTIVES: The blood of patients with anemia demonstrates distinctly lower attenuation in unenhanced CT images. However, the frequent usage of intravenous contrast hampers evaluation of anemia. Spectral detector computed tomography (SDCT) allows for reconstruction of virtual non-contrast images (VNC) from contrast-enhanced data (CE). The purpose of this study was to evaluate whether VNC allow for prediction of anemia. METHODS: Five hundred twenty-two patients with CE-SDCT of the chest and accessible serum hemoglobin (HbS) were retrospectively included. Patients were assigned to three groups (severe anemia, moderate/mild anemia, and healthy) based on recent lab tests (≤ 7 days) for HbS following gender and the WHO definition of anemia. CT attenuation was determined using two ROI in the left ventricular lumen and one ROI in the descending thoracic aorta. ROI were placed on CE and copied to VNC. ANOVA, linear regression, and receiver operating characteristics were used for statistic evaluation. RESULTS: Average HbS was 11.6 ± 2.4 g/dl. Attenuation on VNC showed significant differences between healthy patients, patients with mild/moderate anemia, and severely anemic patients (all p ≤ 0.05). Applying cutoffs of 39.2/37.6 HU and 33.6/32.7 HU allowed to differentiate between healthy, mild/moderately, and severely anemic men/women (AUC 0.857/0.833 and 0.879/0.932). A linear relationship between HbS and attenuation on VNC was established (r2 = 0.54, HbS = - 0.875 + 0.329 × HU). CONCLUSIONS: An approximation of HbS and presence of anemia can be conducted based on simple attenuation measurements in contrast-enhanced SDCT examinations enabled by VNC imaging. KEY POINTS: • While the attenuation of blood is a previously described biomarker for anemia in non-contrast images, virtual non-contrast images from spectral detector CT circumvent this limitation and allow for diagnosis of anemia in contrast-enhanced scans. • Attenuation of blood in virtual non-contrast images derived from spectral detector CT shows a moderate correlation to serum hemoglobin levels. • Presence of anemia be estimated in virtual non-contrast images using proposed cutoffs of 39.2 HU and 37.6 HU for men and women, respectively, to differentiate between healthy and anemic patients.

Virtual monoenergetic images from spectral detector computed tomography facilitate washout assessment in arterially hyper-enhancing liver lesions.

OBJECTIVES: To investigate whether the increased soft tissue contrast of virtual monoenergetic images (VMIs) obtained from a spectral detector computed tomography (SDCT) system improves washout assessment of arterially hyper-enhancing liver lesions. METHODS: Fifty-nine arterially hyper-enhancing lesions in 31 patients (age 65 ± 9 years, M/W 20/11) were included in this IRB-approved study. All patients underwent multi-phase SDCT for HCC screening. MRI, CEUS or biopsy within 3 months served as standard of reference to classify lesions as LiRADS 3 or 4/5. VMIs and conventional images (CIs) were reconstructed. Visual analysis was performed on 40, 60, and 80 kiloelectronvolt (keV) and CIs by 3 radiologists. Presence and visibility of washout were assessed; image quality and confidence of washout evaluation were evaluated on 5-point Likert scales. Signal-to-noise ratio (SNR), lesion-to-liver contrast-to-noise ratio (CNR) (|HUlesion-HUliver|/SDliver) and washout (|HUlesion-HUliver|) were calculated. Statistical assessment was performed using ANOVA and Wilcoxon test. RESULTS: On subjective lesion analysis, the highest level of diagnostic confidence and highest sensitivity for the detection of lesion washout were found for 40-keV VMIs (40 keV vs. CI, 81.3 vs. 71.3%). Image quality parameters were significantly better in low-kiloelectronvolt VMIs than in CIs (p < 0.05; e.g. SNRliver: 40 keV vs. CIs, 12.5 ± 4.1 vs. 5.6 ± 1.6). In LiRADS 4/5 lesions, CNR and quantitative washout values were significantly higher in 40-keV VMIs compared to CIs (p < 0.05; e.g. CNR and washout in 40 keV vs. CIs, 2.3 ± 1.6 vs. 0.8 ± 0.5 and 29.0 ± 19.1 vs. 12.9 ± 6.9 HU, respectively). CONCLUSION: By increasing lesion contrast, low-kiloelectronvolt VMIs obtained from SDCT improve washout assessment of hyper-enhancing liver lesions with respect to washout visibility and diagnostic confidence. KEY POINTS: • Low-kiloelectronvolt virtual monoenergetic images from spectral detector CT facilitate washout assessment in arterially hyper-enhancing liver lesions. • Image quality and quantitative washout parameters as well as subjective washout visibility and diagnostic confidence benefit from low-kiloelectronvolt virtual monoenergetic images.

Virtual mono-energetic images and iterative image reconstruction: abdominal vessel imaging in the era of spectral detector CT.

AIM: To compare the quality of virtual mono-energetic (VMI) and polychromatic images reconstructed with hybrid iterative (PCIHIR) or model-based reconstruction (PCIMBR) derived from dual-layer spectral detector computed tomography (SDCT) in arterial phase images to visualise the aorta and abdominal main branches. MATERIAL AND METHODS: A retrospective review of 50 patients with abdominal arterial phase scans was undertaken. Attenuation, intraluminal noise, and signal-/contrast-to-noise ratio (S-/CNR) were assessed in the PCIHIR, PCIMBR and VMI40keV, VMI70keV, and VMI100keV images. Contrast, noise, and visualization of soft-plaque, and macro-/micro-calcifications were scored in a blinded reading by two radiologists. RESULTS: VMI40keV yielded highest S-/CNR (p≤0.001). VMI70keV and PCIMBR showed comparable SNR (p≥0.999) and yielded higher SNR than PCIHIR. VMI70keV yielded higher CNR than PCIHIR (p<0.001) and PCIMBR (p<0.045). VMI100keV yielded lowest CNR (p≤0.001) and SNR (p≥0.104). In the subjective analysis, VMI40keV outperformed PCIMBR for contrast and noise, PCIMBR scored better than VMI70keV, and the latter scored better than PCIHIR for these categories (all p<0.001). PCIMBR was superior for depiction of soft-plaque and micro-calcifications (p<0.001). VMI100keV visualized micro-calcifications second best (p<0.001) and matched PCIMBR for the depiction of macro-calcifications (p>0.999), while VMI40keV scored second best for depiction of soft-plaque (p<0.020). CONCLUSIONS: VMI40keV and VMI70keV yield better S-/CNR than PCIHIR and PCIMBR; however, PCIMBR visualized arteriosclerotic plaques best, followed by VMI40keV for depiction of soft-plaque and VMI100keV for macro- and micro-calcification. Based on the present findings, PCIMBR on conventional CT and VMI40keV supplemented by VMI100keV on SDCT are recommended for the diagnostic assessment of abdominal arteries.

Medical students' attitude towards artificial intelligence: a multicentre survey.

OBJECTIVES: To assess undergraduate medical students' attitudes towards artificial intelligence (AI) in radiology and medicine. MATERIALS AND METHODS: A web-based questionnaire was designed using SurveyMonkey, and was sent out to students at three major medical schools. It consisted of various sections aiming to evaluate the students' prior knowledge of AI in radiology and beyond, as well as their attitude towards AI in radiology specifically and in medicine in general. Respondents' anonymity was ensured. RESULTS: A total of 263 students (166 female, 94 male, median age 23 years) responded to the questionnaire. Around 52% were aware of the ongoing discussion about AI in radiology and 68% stated that they were unaware of the technologies involved. Respondents agreed that AI could potentially detect pathologies in radiological examinations (83%) but felt that AI would not be able to establish a definite diagnosis (56%). The majority agreed that AI will revolutionise and improve radiology (77% and 86%), while disagreeing with statements that human radiologists will be replaced (83%). Over two-thirds agreed on the need for AI to be included in medical training (71%). In sub-group analyses male and tech-savvy respondents were more confident on the benefits of AI and less fearful of these technologies. CONCLUSION: Contrary to anecdotes published in the media, undergraduate medical students do not worry that AI will replace human radiologists, and are aware of the potential applications and implications of AI on radiology and medicine. Radiology should take the lead in educating students about these emerging technologies. KEY POINTS: • Medical students are aware of the potential applications and implications of AI in radiology and medicine in general. • Medical students do not worry that the human radiologist or physician will be replaced. • Artificial intelligence should be included in medical training.

Improvements of diagnostic accuracy and visualization of vertebral metastasis using multi-level virtual non-calcium reconstructions from dual-layer spectral detector computed tomography.

OBJECTIVE: To evaluate feasibility and diagnostic performance of multi-level calcium suppression in spectral detector computed tomography (SDCT) for assessment of bone metastasis. MATERIALS AND METHODS: Retrospective IRB-approved study on 21 patients who underwent SDCT (120 kV, reference mAs 116) and MRI. Thoracic and lumbar vertebrae (n = 357) were included and categorized as normal (n = 133) or metastatic (n = 203) based on MRI (STIR, T1w, ±contrast). The multi-level virtual non-calcium (VNCa) algorithm computes dynamic soft tissue/calcium pairs allowing for computation of different suppression index levels to address inter-individual variance of prevalent calcium composition weights. We computed images with low, medium, and high calcium suppression indices and compared them with conventional images (VNCa_low/med/high and conventional images (CI)). For quantitative image analysis, regions of interest were placed in normal and metastatic bone. Two readers reviewed the datasets independently in multiple sessions. They determined the presence of vertebral metastases on a per vertebra basis using a binary scale. Statistic assessment was performed using ANOVA with Tukey HSD, Student's T test, and ROC analysis. RESULTS: Attenuation of both normal and metastatic bone was lower in VNCa images than that in conventional images (e.g., CI/VNCa_low, - 46.3 to 238.8 HU/343.3-60.2 HU; p ≤ 0.05). VNCa_low+med improved separation of normal and metastatic bone in ROC analysis (AUC, CI/VNCa_low/VNCa_med = 0.74/0.95/0.98; p ≤ 0.05). In subjective analysis, both sensitivity and specificity were clearly improved in VNCa_low as compared with CI (0.85/0.84 versus 0.78/0.82). Readers showed a good inter-rater reliability (kappa = 0.65). CONCLUSIONS: Multi-level VNCa reconstructed from SDCT improve quantitative separation of normal and metastatic bone and subjective determination of bone metastases when using low to intermediate calcium suppression indices. KEY POINTS: • Spectral detector CT allows for multi-level calcium suppression in CT images and low and medium calcium suppression indices improved separation of normal and metastatic bone. • Thus, multi-level calcium suppression allows to optimize image contrast in regard to dedicated pathologies. • Low-level virtual non-calcium images (index 25-50) improved diagnostic performance regarding detection of metastasis.

Deep brain stimulation of the nucleus basalis of Meynert in Alzheimer's dementia.

Cholinergic neurons of the medial forebrain are considered important contributors to brain plasticity and neuromodulation. A reduction of cholinergic innervation can lead to pathophysiological changes of neurotransmission and is observed in Alzheimer's disease. Here we report on six patients with mild to moderate Alzheimer's disease (AD) treated with bilateral low-frequency deep brain stimulation (DBS) of the nucleus basalis of Meynert (NBM). During a four-week double-blind sham-controlled phase and a subsequent 11-month follow-up open label period, clinical outcome was assessed by neuropsychological examination using the Alzheimer's Disease Assessment Scale-cognitive subscale as the primary outcome measure. Electroencephalography and [(18)F]-fluoro-desoxyglucose positron emission tomography were, besides others, secondary endpoints. On the basis of stable or improved primary outcome parameters twelve months after surgery, four of the six patients were considered responders. No severe or non-transitional side effects related to the stimulation were observed. Taking into account all limitations of a pilot study, we conclude that DBS of the NBM is both technically feasible and well tolerated.

[Hemichorea with Contralateral High Signal Intensity Putaminal Lesion on T1-Weighted Images in Non-Ketotic Hyperglycemia]. / Hemichorea mit T1-hyperintenser Signalalteration im kontralateralen Putamen bei nichtketotischer Hyperglykämie.

A 64-year-old diabetic female patient presented with involuntary unilateral hyperkinetic movements of the left limbs. Cranial MRI showed a contralateral high signal intensity putaminal lesion on T1-weighted images without any signal changes in the T2-weighted images. This finding is characteristic for hemichorea-hemiballism associated with insufficiently treated diabetes mellitus. Additionally, proton MR spectroscopy was performed and revealed a decreased N-acetylaspartate/creatine and N-acetylaspartate/choline ratio, indicating neuronal damage of the contralateral putamen.

Our 2015 approach to invasive pulmonary aspergillosis.

At the University Hospital of Cologne, in general two patient groups at high risk for invasive aspergillosis receive posaconazole prophylaxis: Acute myelogenous leukaemia patients during remission induction chemotherapy and allogeneic haematopoietic stem cell transplant recipients. Other patients at risk undergo serum galactomannan testing three times weekly. At 72-96 h of persisting fever despite broad-spectrum antibiotics, or at onset of lower respiratory tract symptoms a thoracic computed tomography (CT) scan is performed. Without lung infiltrates on CT, IPA is ruled out. In lung infiltrates not suggestive for IPA mycological confirmation is pursued. In patients without posaconazole prophylaxis empiric caspofungin will be considered. CT findings typical for IPA prompt targeted treatment, and mycological confirmation. Bronchoalveolar lavage (BAL) is most important for cultural identification and susceptibility testing, and facilitates diagnosing other pathogens. BAL performance is virtually independent of platelet counts. If despite suggestive infiltrates BAL does not yield the diagnosis, CT-guided biopsy follows as soon as platelet counts allow. Surgery can also be beneficial in diagnosis and treatment of IPA. If the diagnosis of IPA is not established, mucormycosis is a valid concern. In patients with breakthrough IPA during posaconazole prophylaxis liposomal amphotericin B is the drug of choice. If no posaconazole prophylaxis was given, voriconazole is the treatment of choice for IPA.

[Response criteria for malignant melanoma: RECIST and irRC]. / Responsekriterien bei malignem Melanom: RECIST und irRC.

In the field of oncology the response evaluation criteria in solid tumors (RECIST) currently represent the most commonly used and validated radiological response criteria for objective treatment monitoring of conventional chemotherapy. For therapy monitoring of classical cytostatic and cytotoxic tumor therapies RECIST has been tested and successfully validated in many clinical studies. However, with the introduction of novel molecular drugs limitations of these size-based criteria became obvious due to response patterns which are not reflected by RECIST. Thus, for a comprehensive evaluation of modern immunotherapeutic agents new immune-related response criteria (irRC) were developed.This review gives a brief overview of the most important radiological response criteria RECIST 1.0 and 1.1 as well as irRC for malignant melanoma.

[Modern magnetic resonance imaging of the liver]. / Modernes MR-Protokoll für die Leberbildgebung.

Magnetic resonance imaging (MRI) of the liver has become an essential tool in the radiological diagnostics of both focal and diffuse diseases of the liver and is subject to constant change due to technological progress. Recently, important improvements could be achieved by innovations regarding MR hardware, sequences and postprocessing methods. The diagnostic spectrum of MRI could be broadened particularly due to new examination sequences, while at the same time scanning time could be shortened and image quality has been improved. The aim of this article is to explain both the technological background and the clinical application of recent MR sequence developments and to present the scope of a modern MRI protocol for the liver.

[German Radiological Society and the Professional Association of German Radiologists position paper on coronary computed tomography: clinical evidence and quality of patient care in chronic coronary syndrome]. / Positionspapier von DRG und BDR zur Computertomographie des Herzens: Klinische Evidenz und Versorgungsqualität beim chronischen Koronarsyndrom.

This position paper is a joint statement of the German Radiological Society (DRG) and the Professional Association of German Radiologists (BDR), which reflects the current state of knowledge about coronary computed tomography (CT). It is based on preclinical and clinical studies that have investigated the clinical relevance as well as the technical requirements and fundamentals of cardiac computed tomography.

Coronary calcium scoring using virtual non-contrast reconstructions on a dual-layer spectral CT system: Feasibility in the clinical practice.

PURPOSE: To evaluate the clinical applicability of a prototype virtual non-contrast (VNC) reconstruction algorithm based on coronary CT angiography (cCTA) to assess calcified coronary plaques by calcium scoring (CACS). METHODS: Eighty consecutive patients suspected of coronary artery disease were retrospectively included. All patients underwent a cardiac CT using a dual-layer spectral-detector CT system. The standardized acquisition protocol included unenhanced CACS and cCTA. Datasets were acquired using 120 keV. VNC-reconstructions were calculated from the cCTA images at 2.5 mm (VNC group 1), 2.5 of 0.9 mm (group 2), and 0.9 mm (group 3) slice thickness. We compared the Agatston score and Coronary Artery Calcium Data and Reporting System (CAC-DRS) of all VNC reconstructions with the true non-contrast (TNC)-dataset as the gold standard. RESULTS: In total, 73 patients were evaluated. Fifty patients (68.5 %) had a CACS > 0 based on TNC. We found a significant difference in the Agatston score comparing all VNC-reconstructions (1: 1.35, 2: 3.7, 3: 10.4) with the TNC dataset (3.8) (p < 0.001). Correlation analysis of the datasets showed an excellent correlation of the TNC results with the different VNC-reconstructions (r = 0.904-0.974, p < 0.001) with a slope of 1.89-2.53. Mean differences and limits of agreement by Bland-Altman analysis between TNC and group 1 were 83 and -196 to 362, respectively. By using the VNC-reconstructions, in group 1 23 patients (31.5 %), in group 2 10 (13.7 %), and in group 3 23 (31.5 %) were reclassified according to CAC-DRS compared to TNC. Classification according to CAC-DRS revealed a significant difference between TNC and group 1 (p = 0.024) and no significance compared to groups 2 and 3 (p = 0.670 and 0.273). CONCLUSION: The investigated VNC reconstruction algorithm of routine cCTA allows the detection and evaluation of coronary calcium burden without the requirement for an additional acquisition of an unenhanced CT scan for CACS and, therefore, a reduction of radiation exposure.

Detection of intracoronary thrombus by magnetic resonance imaging in patients with acute myocardial infarction.

BACKGROUND: Persistent intracoronary thrombus after plaque rupture is associated with an increased risk of subsequent myocardial infarction and mortality. Coronary thrombus is usually visualized invasively by x-ray coronary angiography. Non-contrast-enhanced T1-weighted magnetic resonance (MR) imaging has been useful for direct imaging of carotid thrombus and intraplaque hemorrhage by taking advantage of the short T1 of methemoglobin present in acute thrombus and intraplaque hemorrhage. The aim of this study was to investigate the use of non-contrast-enhanced MR for direct thrombus imaging (MRDTI) in patients with acute myocardial infarction. METHODS AND RESULTS: Eighteen patients (14 men; age, 61±9 years) underwent MRDTI within 24 to 72 hours of presenting with an acute coronary syndrome before invasive x-ray coronary angiography; MRDTI was performed with a T1-weighted, 3-dimensional, inversion-recovery black-blood gradient-echo sequence without contrast administration. Ten patients were found to have intracoronary thrombus on x-ray coronary angiography (left anterior descending, 4; left circumflex, 2; right coronary artery, 4; and right coronary artery-posterior descending artery, 1), and 8 had no visible thrombus. We found that MRDTI correctly identified thrombus in 9 of 10 patients (sensitivity, 91%; posterior descending artery thrombus not detected) and correctly classified the control group in 7 of 8 patients without thrombus formation (specificity, 88%). The contrast-to-noise ratio was significantly greater in coronary segments containing thrombus (n=10) compared with those without visible thrombus (n=131; mean contrast-to-noise ratio, 15.9 versus 2.6; P<0.001). CONCLUSION: Use of MRDTI allows selective visualization of coronary thrombus in a patient population with a high probability of intracoronary thrombosis.

[Imaging of coronary stents using multislice computed tomography]. / Darstellung von Koronarstents mit der Computertomographie.

Coronary artery stenting has become the most important form of coronary revascularization. With the introduction of drug-eluting stents (DES) the rate of restenosis has declined but due to the delayed formation of intimal tissue the incidence of late (>30 days after stent placement) and very late thrombosis of the stents is higher for DES. Visualization of the stent lumen is possible with multislice computed tomography (MSCT) but blooming artifacts hamper the delineation of the stent lumen. The severity of these artifacts and thus the width of the visible stent lumen depends on several factors, such as the thickness of the stent struts, the design of the stent and the underlying material itself. The most important factor influencing the extent of blooming artifacts is the convolution kernel selected for image reconstruction. Dedicated, edge-enhancing kernels offer superior lumen visualization compared to the soft or medium kernels used for coronary artery imaging. The trade-off using edge-enhancing kernels is an increase in image noise.Despite all efforts undertaken to enhance stent lumen visualization, stent imaging is still a challenge in MSCT. In the majority of stents currently used, sufficient lumen visualization is only possible in stents with a diameter larger than 3 mm. A position of the stent in the proximal segments of the coronary artery tree facilitates delineation of the stent lumen not only because of the relatively little motion but also because of the lesser extent of blooming artifacts obscuring the stent lumen if the stent is oriented perpendicular to the z-axis of the scanner.

Diagnostic value of abdominal follow-up sonography in polytrauma patients: A retrospective study.

In many German trauma centres, it is routine to perform abdominal follow-up sonography (AFS) 6 h after admission for patients with multiple trauma, even if the clinical course is uneventful and multi-slice computed tomography (MSCT) reveals no abdominal pathology. However, this approach is not recommended in the German Guidelines for trauma, and recent studies have questioned the value of AFS to these patients. The present study aimed to evaluate the revised German Guidelines for trauma with respect to the omission of AFS.We included patients with multiple injuries with no clinical signs of abdominal trauma and with normal abdominal MSCT. We collected clinical data of 370 consecutive patients who underwent AFS (Group A) and another 370 consecutive patients who did not undergo AFS (Group B).No abdominal injury was missed by the omission of AFS, and thus, no patient suffered from its omission or benefitted from the use of AFS. In our study population, the negative predictive value of normal MSCT results combined with no clinical signs of abdominal trauma was 100% (95% confidence interval: 99.5%-100.0%).This single-centre study conducted in a large German trauma centre demonstrates AFS to have no utility in the diagnosis of abdominal injury. Moreover, omission of AFS for conscious patients without clinical signs of abdominal trauma and with negative abdominal MSCT does not appear to have negative consequences in terms of missed abdominal injury.Therefore, AFS can be safely omitted in the majority of cases of polytrauma, which simplifies the imaging workup tremendously.

Automatic selection of optimal systolic and diastolic reconstruction windows for dual-source CT coronary angiography.

The aim of this study was to assess the performance of a motion-map algorithm that automatically determines optimal reconstruction windows for dual-source coronary CT angiography. In datasets from 50 consecutive patients, optimal systolic and diastolic reconstruction windows were determined using the motion-map algorithm. For manual determination of the optimal reconstruction window, datasets were reconstructed in 5% steps throughout the RR interval. Motion artifacts were rated for each major coronary vessel using a five-point scale. Mean motion scores using the motion-map algorithm were 2.4 +/- 0.8 for systolic reconstructions and 1.9 +/- 0.8 for diastolic reconstructions. Using the manual approach, overall motion scores were significantly better (1.9 +/- 0.5 and 1.7 +/- 0.6, p < 0.05), but diagnostic image quality was reached in >90% of cases using either approach. Using the automated approach, there was a negative correlation between heart rate and motion scores for systolic reconstructions (rho = -0.26, p < 0.05) and a positive correlation for diastolic reconstructions (rho = 0.46, p < 0.01). For the manual approach, no significant correlation was found for systolic reconstructions (rho = -0.1, p = 0.52), while there was a positive correlation for diastolic reconstructions (rho = 0.48, p < 0.01). Thus, the motion-map algorithm is a useful tool to save time in finding an appropriate reconstruction window in patients with heart rates <70 bpm (diastolic reconstruction) and >80 bpm (systolic reconstruction).

Sensitivity of neurovascular ultrasound for the detection of spontaneous cervical artery dissection.

The reported sensitivity of neurovascular ultrasound (nUS) for detecting spontaneous cervical artery dissection (sCAD) varies from 80% to 96% in the internal carotid artery (ICA) and from 70% to 86% in the vertebral arteries (VA). The aim of this study was to assess the sensitivity of nUS compared to MRI of the neck and MR angiography for the detection of sCAD. Forty consecutive patients with sCAD proven by 1.5T MRI were investigated by nUS within 48 hours of admission. A total of 52 cases of sCAD were detected by MRI, equally distributed (n=26, 50%) in the ICA and VA territories. Two sCADs affecting the ICA (n=2, 8%) and two sCADs of the VA (n=2, 8%) had normal initial nUS findings. The sensitivity of nUS in detecting sCAD is high, about 92% for both vascular territories. However, intramural hematomas may be missed either when they are located outside the arterial segments directly visible by nUS or if they are too small to cause hemodynamically significant stenosis.

[Thoracic and abdominal imaging in immunocompromised patients]. / Radiologische Diagnostik von Thorax und Abdomen bei immunkompromittierten Patienten.

The number of patients with immunosuppression is rising worldwide. The spectrum of diseases and pathogens in these patients differs widely from that of immunocompetent patients due to frequent opportunistic infections. Symptoms are sometimes unspecific, and imaging plays a key role in the management of these patients. The lungs are a frequent site of infection in immunosuppressed patients. Chest X­ray is the starting point for radiological diagnostics, but shows only limited sensitivity and specificity for infections with atypical pathogens. Thus, computed tomography (CT) is of great importance and allows a better distinction between viral, bacterial, or fungal infections, as well as other noninfectious diseases. Even with CT, however, is exact specification of the pathogen unfortunately not possible. CT is also the main diagnostic tool for assessment of the abdomen, particularly in patients presenting with acute abdomen or when sonographic findings are inconclusive. Moreover, CT allows diagnostic and therapeutic interventions such as percutaneous biopsies, or abscess and fluid drainage.