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(1) Background: to test the diagnostic performance of a fully convolutional neural network-based software prototype for clot detection in intracranial arteries using non-enhanced computed tomography (NECT) imaging data. (2) Methods: we retrospectively identified 85 patients with stroke imaging and one intracranial vessel occlusion. An automated clot detection prototype computed clot location, clot length, and clot volume in NECT scans. Clot detection rates were compared to the visual assessment of the hyperdense artery sign by two neuroradiologists. CT angiography (CTA) was used as the ground truth. Additionally, NIHSS, ASPECTS, type of therapy, and TOAST were registered to assess the relationship between clinical parameters, image results, and chosen therapy. (3) Results: the overall detection rate of the software was 66%, while the human readers had lower rates of 46% and 24%, respectively. Clot detection rates of the automated software were best in the proximal middle cerebral artery (MCA) and the intracranial carotid artery (ICA) with 88–92% followed by the more distal MCA and basilar artery with 67–69%. There was a high correlation between greater clot length and interventional thrombectomy and between smaller clot length and rather conservative treatment. (4) Conclusions: the automated clot detection prototype has the potential to detect intracranial arterial thromboembolism in NECT images, particularly in the ICA and MCA. Thus, it could support radiologists in emergency settings to speed up the diagnosis of acute ischemic stroke, especially in settings where CTA is not available. [ABSTRACT FROM AUTHOR]

Introduction: The aim if this study is to find out if contrast between gray (GM) and white matter (WM) on non-enhanced brain CT (NECT) can be enhanced by using a frequency selective non-linear blending. Methods: Thirty consecutive patients (40 % female; mean age 67.73 ± 12.71 years), who underwent NECT of the brain, were retrospectively included in this study. Brain scan readings were performed by two radiologists independently, for NECT and subsequently the images were read using a new frequency selective non-linear blending algorithm (best contrast, BC). Optimal settings of BC for enhanced delineation of anatomical structures were set at an averaged center of 30 HU, averaged delta of 5 HU, and a slope of 5. For contrast-to-noise ratio calculation (CNR), gray and white matter attenuation values were measured for both NECT and BC in different anatomical structures. Results: CNR increase in the gray matter was 5.91 ± 2.45 for the cortical gray matter and 4.41 ± 1.82 for the basal ganglia. The contrast ratio between cortical gray and white matter was 1.87 and 1.7 (basal ganglia/WM) for BC quantification vs. 1.43 (cortex/WM) and 1.33 (basal ganglia/WM) for standard NECT (both p < 0.0001). Improved CNR did not depend on the anatomical structures measured. Conclusion: Frequency selective non-linear blending allows better discrimination between WM and GM and therefore may enhance diagnostic accuracy of NECT. [ABSTRACT FROM AUTHOR]

Purpose: Ischemic brain edema is subtle and hard to detect by computed tomography within the first hours of stroke onset. We hypothesize that non-enhanced CT (NECT) post-processing with frequency-selective non-linear blending (“best contrast”/BC) increases its accuracy in detecting edema and irreversible tissue damage (infarction). Methods: We retrospectively analyzed the NECT scans of 76 consecutive patients with ischemic stroke (exclusively middle cerebral artery territory—MCA) before and after post-processing with BC both at baseline before reperfusion therapy and at follow-up (5.73±12.74 days after stroke onset) using the Alberta Stroke Program Early CT Score (ASPECTS). We assessed the differences in ASPECTS between unprocessed and post-processed images and calculated sensitivity, specificity, and predictive values of baseline NECT using follow-up CT serving as reference standard for brain infarction. Results: NECT detected brain tissue hypoattenuation in 35 of 76 patients (46.1%). This number increased to 71 patients (93.4%) after post-processing with BC. Follow-up NECT confirmed brain infarctions in 65 patients (85.5%; p = 0.012). Post-processing increased the sensitivity of NECT for brain infarction from 35/65 (54%) to 65/65 (100%), decreased its specificity from 11/11 (100%) to 7/11 (64%), its positive predictive value (PPV) from 35/35 (100%) to 65/69 (94%) and increased its accuracy 46/76 (61%) to 72/76 (95%). Conclusions: This post-hoc analysis suggests that post-processing of NECT with BC may increase its sensitivity for ischemic brain damage significantly. [ABSTRACT FROM AUTHOR]

Rationale and Objectives To evaluate the performance of a dedicated computed tomography (CT) software called “bone reading” generating rib unfolded images for improved detection of rib metastases in patients with lung cancer in comparison to readings of 5- and 1-mm axial CT images and 18 F-Fluordeoxyglucose positron emission tomography/computed tomography (FDG-PET/CT). Materials and Methods Ninety consecutive patients who underwent 18 F-FDG-PET/CT and chest CT scanning between 2012 and 2014 at our institution were analyzed retrospectively. Chest CT scans with 5- and 1-mm slice thickness were interpreted blindly and separately focused on the detection of rib metastases (location, number, cortical vs. medullary, and osteoblastic vs. sclerotic). Subsequent image analysis of unfolded 1 mm–based CT rib images was performed. For all three data sets the reading time was registered. Finally, results were compared to those of FDG-PET. Validation was based on FDG-PET positivity for osteolytic and mixed osteolytic/osteoblastic focal rib lesions and follow-up for sclerotic PET-negative lesions. Results A total of 47 metastatic rib lesions were found on FDG-PET/CT plus another 30 detected by CT bone reading and confirmed by follow-up CT. Twenty-nine lesions were osteolytic, 14 were mixed osteolytic/osteoblastic, and 34 were sclerotic. On a patient-based analysis, CT (5 mm), CT (1 mm), and CT (1-mm bone reading) yielded a sensitivity, specificity, and accuracy of 76.5/97.3/93, 81.3/97.3/94, and 88.2/95.9/92, respectively. On segment-based (unfolded rib) analysis, the sensitivity, specificity, and accuracy of the three evaluations were 47.7/95.7/67, 59.5/95.8/77, and 94.8/88.2/92, respectively. Reading time for 5 mm/1 mm axial images and unfolded images was 40.5/50.7/21.56 seconds, respectively. Conclusions The use of unfolded rib images in patients with lung cancer improves sensitivity and specificity of rib metastasis detection in comparison to 5- and 1-mm CT slice reading. Moreover, it may reduce the reading time. [ABSTRACT FROM AUTHOR]

Rationale and Objectives: This study determines the value of whole brain color-coded three-dimensional perfused blood volume (PBV) computed tomography (CT) for the visualization of the infarcted tissue in acute stroke patients. Materials and Methods: Nonenhanced CT (NECT), perfusion CT (PCT), and CT angiography (CTA) in 48 patients with acute ischemic stroke were performed. Whole brain PBV was calculated from NECT and CTA data sets using commercial software. PBV slices in identical orientation to the PCT slices were reconstructed and the area of visual perfusion abnormality on PBV maps was measured. The infarct core in the corresponding PCT slices (CBV <2.0 mL/100 g) was measured automatically with commercial software. The ischemic area on PBV and the infarct core on quantitative PCT were compared using the Pearsons-R correlation coefficient. Significance was considered for P < .05. Results: The quantitative PCT demonstrated a mean infarct core volume of 35.48 ± 32.17 cm3, whereas the volume of visual perfusion abnormality of the corresponding PBV slices was 37.16 ± 37.59 cm3. The perfusion abnormality in PBV was highly correlated with the infarct core of quantitative PCT for area per slice (r = 0.933, P < .01) as well as volume (r = 0.922, P < .01). Conclusions: PBV can serve as surrogate marker corresponding to the infarct core in acute stroke with whole brain coverage. [Copyright &y& Elsevier]

The purpose of our animal study was to evaluate a new computed tomography (CT) subtraction technique for visualization of perfusion defects within the lung parenchyma in subsegmental pulmonary embolism (PE). Seven healthy pigs were entered into a prospective trial. Acute PE was artificially induced by fresh clot material prior to the CT scans. Within a single breath-hold, whole thorax CT scans were performed with a 16-slice multidetector-row CT scanner (SOMATOM Sensation 16; Siemens, Forchheim, Germany) before and after intravenous application of 80 ml of contrast medium with a flow rate of 4 ml/s, followed by a saline chaser. The scan parameters were 120 kV and 100 mAseff, using a thin collimation of 16×0.75 mm and a table speed/rotation of 15–18 mm (pitch, 1.25–1.5; rotation time, 0.5 s). Axial source images were reconstructed with an effective slice thickness of 1 mm (overlap, 30%). A new automatic subtraction technique was used. After 3D segmentation of the lungs in the plain and contrast-enhanced series, threshold-based extraction of major airways and vascular structures in the contrast images was performed. This segmentation was repeated in the plain CT images segmenting the same number of vessels and airways as in the contrast images. Both scans were registered onto each other using nonrigid registration. After registration both image sets were filtered in a nonlinear fashion excluding segmented airways and vessels. After subtracting the plain CT data from the contrast data the resulting enhancement images were color-encoded and overlaid onto the contrast-enhanced CT angiography (CTA) images. This color-encoded combined display of parenchymal enhancement of the lungs was evaluated interactively on a workstation (Leonardo, Siemens) in axial, coronal and sagittal plane orientations. Axial contrast-enhanced CTA images were rated first, followed by an analysis of the combination images. Finally, CTA images were reread focusing on areas with perfusion deficits indicating PE on the color-coded enhancement display. Subtraction was feasible for all seven studies. In one animal, opacification of the pulmonary arteries was suboptimal owing to heart insufficiency. In the remaining six pigs, a total of 37 perfusion defects were clearly assessable downstream of occluded subsegmental arteries, showing lower or missing enhancement compared with normally perfused lung parenchyma. Indeterminate findings from CTA showed typical PE perfusion defects in four out of six cases on CT subtraction. Additionally, 22 peripheral triangular-shaped enhancement defects were delineated. Nine of these findings were reclassified as definitely being caused by PE on second reading of the CTA data sets. Our initial results have shown that this new subtraction technique for perfusion imaging of PE is feasible, using routine contrast delivery. Dedicated examination protocols are mandatory for adequate opacification of the pulmonary arteries and for optimization of data sets for subsequent subtraction. Perfusion imaging allows a comprehensive assessment of morphology and function, providing more accurate information on acute PE. [ABSTRACT FROM AUTHOR]

Rationale of this study was to evaluate whether unfolded rib images enhance time efficiency in detection of rib fractures and time efficiency in patients with acute thoracic trauma. 51 subsequent patients with thoracic trauma underwent 64-slice computed tomography. 1mm thick axial slices were reformatted using a commercially available post-processing software application generating rotatable unfolded rib images. Diagnostic accuracy was evaluated by 3 readers and compared to multiplanar reformations of the original CT images. Reformation and evaluation times were recorded. 116 rib fractures were detected. The multiplanar reformation analysis yielded a sensitivity of 87.9%/93.9%/79.7% with a specificity of 97%/97%/82.2%, whilst the unfolded rib image analysis yielded a sensitivity of 94.8%/94.8%/92.2% and a specificity of 85.2/87.8%/82.4 (p=0.06/0.8/0.04) with high inter-observer agreement (k=0.79-0.85). The mean reading time for the multiplanar reformations was significantly longer (reader 1: 103.7 ± 27.1s/reader 2: 81.8 ± 40.6s/reader 3: 154.3 ± 39.2s) than the evaluation of the unfolded rib images (19.4 ± 4.9s/26.9 ± 15.0s/49.9 ± 18.7s; p<0.01). Concluding, the unfolded rib display reduces reading time for detection of rib fractures in acute thoracic trauma patients significantly and does not compromise the diagnostic accuracy significantly in experienced radiologists. However, unexperienced readers may profit from use of this display. [ABSTRACT FROM AUTHOR]